number
/ˈnʌmbə//ˈnʌmbɚ/noun
Definitions
An abstract entity used to describe quantity.
Example: Zero, one, −1, 2.5, and pi are all numbers.
A numeral: a symbol for a non-negative integer.
Example: The number 8 is usually made with a single stroke.
An element of one of several sets: natural numbers, integers, rational numbers, real numbers, complex numbers, and sometimes extensions such as hypercomplex numbers, etc.
Example: The equation e^{i\pi}+1=0 includes the most important numbers: 1, 0, \pi, i, and e.
(Followed by a numeral; used attributively) Indicating the position of something in a list or sequence. Abbreviations: No or No., no or no. (in each case, sometimes written with a superscript "o", like Nº or №). The symbol "#" is also used in this manner.
Example: Horse number 5 won the race.
verb
Definitions
To label (items) with numbers; to assign numbers to (items).
Example: Number the baskets so that we can find them easily.
To total or count; to amount to.
Example: I don’t know how many books are in the library, but they must number in the thousands.