quantity

quantity — noun

1. The total size or count of something that can be weighed, measured, or expressed

1.nounA2
Definition

The total size or count of something that can be weighed, measured, or expressed as a number — for instance, the volume of water in a swimming pool or the number of seats in a theatre.

Example

The recipe calls for a small quantity of salt, about half a teaspoon.

adjective + quantity of + uncountable noun

Jessica checks the quantity of milk left in the carton each morning before school.

quantity of + noun for checking amount

Common collocations
  • small quantity
  • large quantity
  • vast quantity
  • total quantity
  • sufficient quantity
  • quantity of
  • quantities of
  • in quantity
Synonyms
  • amount

    more common in everyday speech; used especially for uncountable things (amount of water, amount of time)

  • volume

    specifically for three-dimensional space or the amount of sound; more technical than quantity

  • number

    used only with countable items (number of people, number of chairs); not interchangeable with quantity for uncountable nouns

Grammar Patterns

quantity of + noun

quantities of + noun

adjective + quantity of + noun

Usage Note

Quantity is the most general word for 'how much' or 'how many'. It is often contrasted with quality, which describes how good something is rather than how much of it exists. In everyday speech, 'amount' is more common for uncountable nouns and 'number' for countable nouns; 'quantity' sounds slightly more formal.

Common Mistakes

I need a big quantity of apples for the party.
I need a large number of apples for the party.
For countable items, 'a large number of' or 'many' sounds more natural than 'a large quantity of' in everyday conversation.

2. a large or more-than-enough amount of something — used when the size or number i

2.nounB1
Definition

a large or more-than-enough amount of something — used when the size or number is important or impressive, such as a quantity of rice stored in a warehouse or a quantity of steel needed for a building project.

Example

The warehouse contains a quantity of rice that feeds a whole region for a month.

a quantity of + noun (large amount in storage)

Arjun ordered a quantity of steel beams for the new bridge across the river.

ordered a quantity of + noun (construction context)

Common collocations
  • a quantity of
  • quantities of
  • sheer quantity
  • in quantity
  • buy in quantity
Synonyms
  • abundance

    more emphatic and positive; suggests more than enough (an abundance of food)

  • mass

    suggests a solid, undivided bulk; used for physical substances (a mass of papers)

  • bulk

    focuses on size or volume rather than number (the bulk of the shipment)

Grammar Patterns

a quantity of + noun (singular/uncountable)

quantities of + noun

Usage Note

In this sense, 'a quantity of' often implies a notably large amount, but the exact size depends on context — a 'quantity of medicine' might be just a few bottles while a 'quantity of grain' could be many tonnes. The phrase 'in quantity' (without 'a' or 'of') means 'in large amounts' and comes before a verb or at the end of a clause.

Common Mistakes

The company bought quantity of wood.
The company bought a quantity of wood.
When used to mean 'a large amount', the indefinite article 'a' is required before 'quantity of'.

3. a value or amount that can be expressed as a number in a mathematical equation o

3.nounB2
Definition

a value or amount that can be expressed as a number in a mathematical equation or scientific calculation — for example, the speed of light, the temperature of a liquid, or the variable x in an algebraic formula.

Example

The students learned to solve for the unknown quantity x in the algebraic equation.

unknown quantity (math term for a variable)

In E = mc², each letter stands for a physical quantity like energy or mass.

physical quantity (science term)

Common collocations
  • physical quantity
  • unknown quantity
  • vector quantity
  • scalar quantity
  • measurable quantity
  • variable quantity
Synonyms
  • value

    more common in everyday maths (the value of x); narrower than quantity, which includes the concept of measurability

  • magnitude

    more technical; emphasises size or scale rather than count (magnitude of an earthquake)

  • measure

    focuses on the process or result of measuring (a measure of distance)

Grammar Patterns

a/the + adjective + quantity

physical/mathematical/unknown + quantity

Usage Note

In mathematics and science, 'quantity' refers specifically to a measurable property that can be assigned a number and a unit. Unlike sense 1, this sense is always technical and precise. Common compound terms include 'physical quantity', 'vector quantity', 'scalar quantity', and 'unknown quantity'.

Common Mistakes

In math class, we learned about quantity x.
In math class, we learned about the quantity x.
In the mathematical sense, 'quantity' nearly always takes a determiner (the, a, this) before it.
Idioms

an unknown quantity

idiom

A person or thing that you do not know much about yet.

The new student is still an unknown quantity to the teacher.

Is this investment an unknown quantity for the company?

Word family

Synonym discussion

Sense: noun/1

All three words refer to 'how much' or 'how many', but they differ in which types of nouns they pair with. 'Amount' is the most common everyday word and is used with uncountable nouns: you talk about the amount of water, time, or money. 'Number' is reserved for countable items: the number of people, chairs, or errors. 'Quantity' sits between the two — it can be used with both countable and uncountable nouns (quantity of milk or quantity of books), but it sounds slightly more formal than 'amount' and often implies that the thing is being measured precisely. 'Volume' is more specific: it refers to the three-dimensional space something occupies (volume of a box) or the loudness of sound (volume of the music), and is the most technical of the four. For example: 'The amount of sugar in the recipe was wrong' (everyday); 'A large number of guests arrived early' (countable); 'The laboratory recorded the quantity of gas produced' (formal, precise); 'The volume of water in the tank is 200 litres' (three-dimensional space).

amount ↗number ↗volume ↗

Common collocations

Nouns

Adverbs

Phrases

  • in large quantities
  • in small quantities
  • a quantity of
  • quantities of

Prepositions

Etymology

LatinOld FrenchEnglish

The word 'quantity' comes from Latin 'quantitas', which means 'how great' or 'how much'. It is built on 'quantus' ('how much') plus the noun suffix '-itas' ('-ity'). The word entered English through Old French 'quantite' in the 1300s, originally keeping the general meaning of 'a portion or amount'. By the 1500s it had developed the more specific sense of 'a large amount'. The mathematical meaning — a measurable value in an equation — became common during the scientific revolution of the 1600s and 1700s as scholars like Newton and Galileo needed precise terms for describing physical properties.