a symbol for an amount, or an amount or identifying code

A number of + plural noun means several or many; the number of refers to the total amount.

to give numbers to things

Number can be used in the passive: The seats are numbered.

for each one

Per is used in rates and measurements to mean for each.

an item, amount, or part of something

piece of 后可接不可数名词，表示“一份；一条”。

a unit of weight equal to 1,000 kilograms, or a very large amount

tons of 在口语中表示“很多”。

a unit of distance equal to 1,760 yards

Mile is countable.

the number 1,000

具体数字后通常不用复数；表示大量时说 thousands of。

the branch of maths using symbols

Algebra uses letters and symbols to represent numbers.

a single symbol from 0 to 9

A digit is one symbol in a number.

a finger or toe

This anatomical use includes fingers and toes.

a level or amount

Use this sense for extent.

an academic qualification

Use degree in + subject.

a unit for temperature or angles

Use degrees for temperature and angles.

physical substance that takes up space

Matter is uncountable when it means physical substance.

the force that pulls objects towards one another, especially towards the Earth

Gravity is uncountable. Earth's gravity pulls unsupported objects towards the ground; it is a force, not a name for an object's weight.

the seriousness or importance of a situation

This formal sense is unrelated to physical falling. The gravity of a problem means how serious it is.

added to a number or amount

数学表达中 plus 表示“加”。

an advantage of a situation

作名词时常用 a plus 或 a big plus。

used to add another point or reason

口语中常置于句首，补充另一个理由或信息。

a long thin stick or one end of the Earth

Pole can be a long stick or either of the two ends of the Earth.

measure or express something as a number

Quantify means show an amount exactly by using numbers.

an amount or number of something

Quantity focuses on how much or how many of something there is.

connected with the subject of mathematics

通常放在名词前，如 mathematical problem。

based on exact calculation

常修饰 calculation、method、precision 等抽象名词。

an expert in mathematics

指职业或专业身份，不等同于所有会做数学题的人。

the subject of mathematics

表示学科时通常不加 a，也通常接单数谓语：Maths is difficult for him。

a computer program for a phone, tablet, or computer, especially one for a particular task

app 是 application 的常用缩略形式，必须小写书写。 常说 download/install/use an app；app 常与手机或平板使用场景连用。

a mobile telephone

Cellphone is especially common in American English; British English often says mobile phone.

using computer technology or electronic signals

Digital relates to computer-based technology.

facts or information collected for analysis or use

Data was originally plural. Scientific writing often uses a plural verb, as in the data show; general usage also treats it as an uncountable noun with a singular verb. Use a piece of data, not a data, for one item.

a piece of equipment with moving parts that does work

Machine is countable.

the physical parts of a computer or other electronic system

Hardware is uncountable for physical computer equipment, as opposed to software.

tools, metal equipment, and small items used for building or repairs

Hardware can also mean tools and metal equipment used for building or repair.

a set of letters, numbers, signs, or rules used to give information or instructions

由语境决定是计算机代码、进入用的密码，还是一套规则；postcode 中的 code 指邮政编码的一部分。

to put information into a code, or to write instructions for a computer

code 可及物：code the results；也可说 code an app。不要把名词 code 和动词 code 混作同一词性。

a flat device or object used to store information

Disk commonly refers to a computer storage device.

to copy a file or program from the internet to a device

动词重音在第二音节：/ˌdaʊnˈləʊd/；后直接接文件、应用等作宾语。

a file that has been copied from the internet

名词重音在第一音节：/ˈdaʊnləʊd/；常指下载得到的文件或一次下载。

a device used to take photographs or record video

take a photo with a camera；on camera 表示被镜头拍到。

a machine that can carry out tasks automatically

可指工业、服务或教学机器人。

a very small robot designed to work at the scale of nanometres

Nanobot is a technology word; nano- means extremely small.

a small solid piece or dose of medicine that you swallow

medicine tablet 比 pill 更强调“片剂”。

a small flat computer with a touch screen

现代语境中 tablet 也常指平板电脑。

computer programs used to do particular tasks

software 通常不可数；不说 softwares。

the worldwide computer network that connects people and information

Internet is normally used with the: on the Internet; it is often written with a capital I in careful writing.

wireless internet access

Wi-Fi is a wireless way to connect devices to the internet.

short for artificial intelligence, technology that enables computers to learn or make decisions

AI 是 artificial intelligence 的缩写，两个字母均大写。

a small animal with a long tail

The plural of the animal mouse is mice.

a small device used to control a computer

This sense refers to a computer device.

a piece of material made of crossed threads or wires, used for catching, protecting, or separating things

A net is a physical mesh; do not confuse this literal noun with the Internet.

recently made, obtained, introduced, or discovered

可修饰具体事物，也可修饰方法、证据等抽象名词。

to make information or a system more current

动词 update 重音在第二音节：/ʌpˈdeɪt/。

new information about a situation

名词 update 重音在第一音节：/ˈʌpdeɪt/。

available for use when needed

spare time 指空闲时间；spare key 指备用钥匙。

to give time or prevent someone from suffering something

spare sb sth 表示使某人免受某事。

a radio or TV programme, or to send one out

作动词时过去式和过去分词常仍为 broadcast。

a route for water, messages, or television

Channel can be a narrow stretch of water or a route through which information is sent.

a story or event recorded as moving pictures for people to watch

In British English, film is the ordinary word for a movie; it can also describe a documentary.

a very thin layer of material, or material used for taking photographs

A film of something is a thin layer covering a surface; this is different from a film meaning a movie.

to record people or events with a camera for a film or video

Film takes the person, event, or scene that the camera records as its object.

the impression that a person, organisation or product gives to others

Image in this sense concerns how others see someone or something, which may differ from reality.

a picture or visible representation of someone or something

An image may be a photograph, a picture on a screen or a representation carved in stone or wood. Name the medium when the type is important.

a picture created in the mind by words, especially in poetry

A literary image creates a mental picture and may suggest a wider meaning; it is not necessarily a literal illustration.

an image, drawing, or photograph

picture 可指图画或照片。

to imagine a situation or person in your mind

picture + sb doing sth 表示想象某人在做某事。

a large printed notice or picture put up in a public place

poster 的核心义是张贴或展示的海报；本卡不把它解释成由邮政义直接派生。

a flat surface that shows pictures or information

screen 可指电子设备的显示屏，也可指电影院里的银幕。

to check people or information before allowing or using them

常用于正式场合，强调先检查再决定是否放行或采用。

a small disc used to store music or computer data

Say the letter names separately. CD is countable; its usual plural is CDs.

a disc that stores films or other digital data

DVD is pronounced as separate letter names. A DVD can hold more data than a CD.

a compact disc that stores video and sound

Read VCD as separate letter names. It is a video format based on CD technology, distinct from DVD.

provide someone or something with what is needed

Equip somebody with something gives needed tools or skills; be equipped with describes what something has.

the tools or machines needed for an activity

Equipment is uncountable: say some equipment or a piece of equipment, not equipments.

a tool with a sharp blade, used for cutting

The plural of knife is knives.

a tool with a heavy head used for hitting nails

A hammer is the tool; drive or hit describes the action done with it.

to join things or recognise a relationship

Connect A to B names the two things joined; connect with can mean form a relationship.

a link between people, things, or ideas

This sense describes a relationship or link between ideas or people.

a transport or service link that lets one journey or system continue

A train connection is the service or link that connects two parts of a journey.

a connection between people, things or ideas, or a way to reach an online page

Use between for a connection involving two things and to for a destination. A website link is one specific kind of connection.

to join things together or show a connection between them

Link can describe a physical connection or an association between ideas and events. Do not assume that linked events necessarily cause each other.

to control and use a machine or piece of equipment

This use takes a machine or device as its object.

to work or function in a particular way

This use describes how a system or organisation functions.

to perform surgery on someone

Operate on is the medical construction and takes the patient after on.

the way a machine or system works

In operation describes a machine, system, or rule that is working.

a medical procedure performed by a surgeon

A surgical operation is a countable medical procedure.

an organised activity or planned piece of work

This sense names an organised activity, not a machine’s operation.

a person or company that controls equipment or provides a service

Operator names the person or organisation carrying out or managing an operation.

connected with practical skills, machines, or a special subject

technical 与 technology 相关，但 technical 是形容词。

a particular way of doing something skillfully

technique 强调做事的具体方法或技巧。

connected with technology

主重音在 /lɒdʒ/ 音节；注意不要把重音误放在开头。

scientific knowledge used to make useful things

technology 通常不可数，泛指科技。

an object used to do a particular kind of work

tool 既可指手工工具，也可指完成任务的方法或手段。

a box or case for keeping tools in

toolbox 是 tool 与 box 的复合词。

a tool for digging

Spade is countable; use a spade for one digging tool and with a spade to describe the tool used.

a thin metal strand that carries electricity

Wire is metal thread used for electricity or fastening things.

connect equipment or a building using electrical wires

Use wire something to something for an electrical connection; wiring a building requires trained workers.

a thin cord for tying

String is uncountable for cord used to tie things, but countable for one cord on an instrument.

having strings

Stringed usually appears before instrument to describe one whose stretched strings make the sound.

a device for electricity or for blocking a hole

名词可指电器插头；英式常说 plug socket。

to connect an electrical device to a power supply

plug in 表示插上电源。

a place where a plug fits

A socket is the place in a wall where an electrical plug is connected.

a seed or fruit with a hard shell and an edible inner part

Nut is countable. The everyday food category includes several kinds of seeds as well as nuts in the strict botanical sense.

a small metal part with a threaded hole that fits onto a bolt

A nut fits around a bolt; it is not the long metal bolt itself. Tighten or loosen a nut by turning it.

a valuable yellow metal used for jewellery, coins, and decoration

Gold is uncountable when it means the metal.

a bright yellow colour like the colour of gold

Gold can name the colour as well as the metal.

the top prize or first-place result in a competition

Win gold means win a gold medal or first prize; it does not necessarily mean receive the metal itself.

bright yellow like gold

Golden describes a colour or appearance similar to gold.

very valuable, successful, or fortunate

Golden is figurative in phrases such as a golden opportunity, meaning an unusually valuable chance.

a very hard valuable stone used in jewellery

Diamond can be a precious stone or a four-sided geometric shape; the context distinguishes them.

a place where minerals are taken from the ground

Mine means an underground or open site for taking coal, metal, or other minerals from the earth.

to dig minerals such as coal or gold out of the ground

Use mine coal for the material taken out, and mine for gold for the mineral being sought.

a natural substance found in rocks or needed by the body

Mineral can name a substance from the earth or a nutrient such as calcium or iron.

a valuable grey-white metal

silver 作金属名词通常不可数。

having the colour of silver

作形容词时通常放在名词前。

a flexible material used for many products

材料义通常不可数。

an object used for removing pencil marks or cleaning a board

英式英语中 rubber 可指橡皮。

not flexible or not willing to change

Rigid can describe a material that will not bend or a rule that allows no change.

not mixed with anything else or not polluted

Pure describes something not mixed with other substances or influences.

a hard material such as iron, gold, or silver

Metal is uncountable when it means the material in general.

a substance used for making things

Material is uncountable for substance in general, but countable for a particular kind of material.

the part of plant food that the body does not fully digest

Fibre is uncountable when referring to a component of food. The spelling fiber is used in American English.

a thin thread, or material made from such threads

A fibre is one thread; fibres can be the threads that make up cloth. Natural fibres such as cotton contrast with synthetic fibres.

a sticky earth used to make pottery and bricks

Clay is normally uncountable. It is soft enough to shape when wet and can become hard when fired.

an instrument that makes very small objects appear large enough to examine

Use through a microscope for looking through the instrument, and under a microscope for the specimen being examined. A microscope reveals small details, unlike a telescope used for distant objects.

an animal belonging to a group of reptiles that first lived millions of years ago

Dinosaur is countable. Dinosaur can also act before a noun, as in dinosaur bones; this form stays singular even when the following noun is plural.

an empty area that is available for people or things

space 作空间义通常不可数。

the area beyond the Earth’s atmosphere

表示宇宙空间时通常不加冠词。

relating to atomic nuclei or the energy released from them

Nuclear is pronounced with the sequence /kliə/. It describes energy technology as well as weapons using energy from atomic nuclei.

to combine two or more things together

Mix takes the things combined as its object.

a combination of different things

Mixture is countable.

a fact or event that can be observed

复数是 phenomena，不是 phenomenons。

more than two but not many

several 后接可数名词复数，也可单独作代词。

one only, or travelling in one direction without returning

single 可强调“只有一个”；a single ticket 指单程票，every single ... 表示“每一个”。

not married or in a relationship

用于成年人时可表示未婚或没有伴侣。

not common

Rare describes something not found or seen often.

chosen without a planned order

At random means without a planned method of choosing.

a moving line of water on the sea or a lake

wave 作名词表示水面上的波浪。

to move your hand to greet or say goodbye

wave at 后接挥手致意的对象。

how fast someone or something moves

speed 通常不可数；at high speed 表示高速。

to move or happen quickly

speed up 表示加速。

more than enough; available in large quantities

Abundant is normally used before a noun or after be to describe a large supply.

more than enough for a purpose

常修饰 time、evidence、space，强调“足够而有余”。

more than usual or needed

Extra comes before a noun to mean additional; it is often used for time, money, help, or tickets.

extremely large in size, amount, or degree

enormous 比 very big 语气强，既可写实际尺寸，也可写数量、影响或压力。

a large amount or lump, or the amount of matter in an object

a mass of 后可接可数复数或不可数名词。

very large, heavy, or serious

强调规模、重量或影响都很大。

a building or group of buildings where goods are made by machines

A factory is a place for manufacturing; a farm is a place for growing crops or keeping animals.

the production of goods in factories, and the businesses involved in it

Industry is uncountable when it means industrial production or business activity in general.

a hard black substance burned for energy

coal 通常不可数；一块煤说 a piece of coal。

flames and heat, or a destructive burning event

本卡只收录来源明确支持的名词义；用于取暖的 fire 仍是“火”这一核心义。

a change or difference in amount, quality or form

Variation can be uncountable for changing or differing in general, and countable for individual differences. In introduces the feature that changes.

a form of something that differs slightly from another form

A variation on a recipe, story or design keeps its basic idea while changing some details.

a changed musical version of a theme or melody

In music, variations repeat a recognisable theme while changing features such as rhythm or harmony.

containing many different kinds or showing a wide range

Varied describes variety within something, including a singular noun such as programme. Various normally comes before a plural noun to mean several different ones.

the quality of having different kinds or experiences rather than always the same thing

Variety is uncountable for diversity itself. Add variety to means make something less repetitive.

a type of something, or a range of different types

A variety of followed by a plural noun means a range of different things. A named plant variety is one particular kind; varieties is its plural.

several different kinds of people or things

Various normally comes before a plural noun and does not take a before it. Compare various activities with a varied programme, which is one programme containing different activities.

to change or be different according to time, place or circumstances

Without an object, vary describes differences or change. In names the feature; from ... to ... can compare places, people or values.

to change something, especially to make it less repetitive

With a direct object, vary means deliberately change that thing. It can help avoid repetition rather than simply replace something once.

a general direction in which something changes

A trend is a general direction of change over time, not a single event.

continuing and not yet finished

ongoing 只作形容词，常放在名词前；不作动词使用。