c. 1300, "to count," from Old French nombrer "to count, reckon," from nombre (n.) "number" (see number (n.)). Meaning "to assign a distinctive number to" is late 14c.; that of "to ascertain the number of" is from early 15c. Related: Numbered; numbering.

1640s, "treating of a thing as the same as another; act of making or proving to be the same," from French identification, probably from identifier (see identify). Psychological sense of "becoming or feeling oneself one with another" is from 1857. Meaning "act or process of determining the identity of something" is from 1859. Meaning "object or document which marks identity" is from 1947 (short for identification tag, card, etc.).

c. 1300, "sum, aggregate of a collection," from Anglo-French noumbre, Old French nombre and directly from Latin numerus "a number, quantity," from PIE root *nem- "assign, allot; take."

Meaning "written symbol or figure of arithmetic value" is from late 14c. Meaning "single (numbered) issue of a magazine" is from 1795. Colloquial sense of "a person or thing" is by 1894. Meaning "dialing combination to reach a particular telephone receiver" is from 1879; hence wrong number (1886). The modern meaning "musical selection" (1885) is from vaudeville theater programs, where acts were marked by a number. Earlier numbers meant "metrical sound or utterance, measured or harmonic expression" (late 15c.) and, from 1580s, "poetical measure, poetry, verse."

Number one "oneself" is from 1704 (mock-Italian form numero uno attested from 1973); the biblical Book of Numbers (c. 1400, Latin Numeri, Greek Arithmoi) is so called because it begins with a census of the Israelites. Childish slang number one and number two for "urination" and "defecation" attested from 1902. Number cruncher is 1966, of machines; 1971 of persons. To get or have (someone's) number "have someone figured out" is attested from 1853; to say one's number is up (1806) meaning "one's time has come" is a reference to the numbers on a lottery, draft, etc. The numbers "illegal lottery" is from 1897, American English.

1590s, "one, two, three," etc. as opposed to ordinal numbers "first, second, third," etc.; so called because they are the principal numbers and the ordinals depend on them (see cardinal (adj.)).

acronym for personal identification number, 1981; from the first it has been used with a redundant number.

"erroneous identification," 1858, from mis- (1) + identification.

also ID (but pronounced as separate letters), short for identification, attested from 1955.

"soldier's identity disk," 1918, U.S. slang, from dog (n.) + tag (n.1). So called perhaps from resemblance to the identification/license tag on dog collars.

"pertaining to or relating to number, denoting number," 1620s, from Latin numerus "a number" (see number (n.)) + -ical. Perhaps by influence of French numérique "of a number or numbers." Related: Numerically.

"to number more than, exceed in number," 1660s, from out- + number (v.). Related: Outnumbered; outnumbering.