num·ber 
(nŭmbər)
(nŭmbər)n.
1. Mathematics
a. A member of the set of positive integers; one of a series of symbols of unique meaning in a fixed order that can be derived by counting.
b. A member of any of the following sets of mathematical objects: integers, rational numbers, real numbers, and complex numbers. These sets can be derived from the positive integers through various algebraic and analytic constructions.
2. numbers Arithmetic.
3.
a. A symbol or word used to represent a number.
b. A numeral or a series of numerals used for reference or identification: his telephone number; the apartment number.
4.
a. A position in an ordered sequence that corresponds to one of the positive integers: the house that is number three from the corner; ranked number six in her class.
b. One item in a group or series considered to be in numerical order: an old number of a magazine.
5. A total; a sum: the number of feet in a mile.
6. An indefinite quantity of units or individuals: The crowd was small in number. A number of people complained.
7. numbers
a. A large quantity; a multitude: Numbers of people visited the fair.
b. Numerical superiority: The South had leaders, the North numbers.
8. Grammar The indication, as by inflection, of the singularity, duality, or plurality of a linguistic form.
9. numbers
a. Metrical feet or lines; verses: "These numbers will I tear, and write in prose" (Shakespeare).
b. Obsolete Poetic meter.
10. numbers Archaic Musical periods or measures.
11. numbers (used with a sing. or pl. verb) Games A numbers game.
12. Numbers (used with a sing. verb) See Table at Bible.
13. One of the separate offerings in a program of music or other entertainment: The band's second number was a march.
14. Slang A frequently repeated, characteristic speech, argument, or performance: suspects doing their usual number—protesting innocence.
15. Slang A person or thing singled out for a particular characteristic: a crafty number.
v. num·bered, num·ber·ing, num·bers
v.tr.
1. To assign a number to or mark with a number: Did you number the pages of the report?
2. To determine the number or amount of; count: Tickets sold for the show were numbered at 500.
3. To total in number or amount; add up to: The ships in the harbor number around 100.
4. To include in a group or category: He was numbered among the lost.
5. To limit or restrict in number: Our days are numbered.
v.intr.
Idioms: 1. To call off numbers; count: numbering to ten.
2. To have as a total; amount to a number: The applicants numbered in the thousands.
by the numbers
1. In unison as numbers are called out by a leader: performing calisthenics by the numbers.
2. In a strict, step-by-step or mechanical way.
do a number on Slang
To defeat, abuse, or humiliate in a calculated and thorough way.
get/have (someone's) number
To determine or know someone's real character or motives.
without/beyond number
Too many to be counted; countless: mosquitoes without number.
[Middle English nombre, from Old French, from Latin numerus; see nem- in the Appendix of Indo-European roots.]
number·er n.
Usage Note: As a collective noun number may take either a singular or a plural verb. It takes a singular verb when it is preceded by the definite article the: The number of skilled workers is increasing. It takes a plural verb when preceded by the indefinite article a: A number of the workers have learned new skills.