1 number /ˈnʌmbɚ/ noun
plural numbers
1 number
plural numbers
Learner's definition of NUMBER
[count] : a word or symbol (such as “five” or “16”) that represents a specific amount or quantity
see also cardinal number, ordinal number, prime number, whole number
: a number or a set of numbers and other symbols that is used to identify a person or thing
abbreviation No. or no. see also registration number, serial number, social security number
: a person who is identified by a number and not treated in a personal or friendly way
: phone number
see also 800 number
: the total amount of people or things
often + of
numbers [plural] : a large group of people or things
used to indicate the position of someone or something in a numbered list or series
abbreviation No. or no.
: the version of a magazine, newspaper, etc., that is published at a particular time
abbreviation No. or no.
[singular] formal : a group of people
[count] : a song or dance that is usually performed as part of a concert or performance
[count] informal : someone or something that is attractive or desirable
numbers [plural] : numbers that show amounts of money that are spent, earned, or needed
numbers [plural] chiefly US
: numbers that show how many people are listening to or watching a particular radio or television program
: numbers that show how a person (such as an athlete) has performed in the past
numbers [plural] US : a gambling game in which people bet on which numbers will be chosen each day often used before another noun
[noncount] grammar : the quality of a word form that shows whether the word is singular or plural

bad/good (etc.) with numbers

: bad, good, etc., at using numbers (such as for adding, subtracting, multiplying, and dividing)

beyond number

formal + literary
: too many to count

by numbers

or US by the numbers
: in a way that follows the rules or instructions but that is not interesting or original

do a number on

: to have a very bad effect on (someone or something) : to hurt or damage (someone or something)

have someone's number

: to be able to deal with or defeat someone easily especially because you know or understand that person so well

without number

: too many to count

your number is up

◊ If your number is up, you are about to suffer or die.
2 number /ˈnʌmbɚ/ verb
numbers; numbered; numbering
2 number
numbers; numbered; numbering
Learner's definition of NUMBER
[+ object] : to give a number to (someone or something in a series) : to label or identify (people or things in a series) with a number
used to indicate a total amount
[linking verb]
[no object]
somewhat formal : to include (someone or something) as part of a larger group + among or with
[+ object]
usually used as (be) numbered
[no object]

days are numbered

used to say that someone or something will die, fail, or end soon