late 14c., "private, pertaining to the self or to a self-conscious individual; performed by the individual himself," from Old French personal (12c., Modern French personnel), from Late Latin personalis "pertaining to a person," from Latin persona (see person).
The meaning "applicable to, directed at, or aimed at some particular person" (usually in a hostile manner) is attested from 1610s. Designating an official or employee attached to one's person (as in personal secretary) by 1928.
The noun sense of "newspaper item about private matters" is attested from 1888. As "a classified ad addressed to an individual," it is recorded from 1861. Personal computer is from 1976.
c. 1600, "sameness, oneness, state of being the same," from French identité (14c.), from Medieval Latin identitatem (nominative identitas) "sameness," ultimately from Latin idem (neuter) "the same" (see idem). [For discussion of Latin formation, see entry in OED.] Earlier form of the word in English was idemptitie (1560s), from Medieval Latin idemptitas. Term identity crisis first recorded 1954. Identity theft attested from 1995. Identity politics is attested by 1987.
"[I]dentity politics" [is] a phrase with notably wide currency in gay and lesbian communities. In common usage, the term identity politics refers to the tendency to base one's politics on a sense of personal identity—as gay, as Jewish, as Black, as female ..... [Diana Fuss, "Essentially Speaking," 1989]
c. 1300, "bear testimony," from witness (n.). Meaning "affix one's signature to (a document) to establish its identity" is from early 14c. Meaning "see or know by personal presence, observe" is from 1580s. Related: Witnessed; witnessing.
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.).
1610s as a term in logic; general sense of "being the same or very similar" is from 1630s, from Medieval Latin identicus "the same," from Late Latin identitas "identity, sameness," ultimately from combining form of Latin idem "the same" (see idem). Replaced Middle English idemptical (late 15c.), from Medieval Latin idemptitas "identity," from Latin idem. Related: Identically.
1640s, "regard as the same," from French identifier, from identité (see identity). Sense of "determine the identity of, recognize as or prove to be the same" first recorded 1769. Meaning "make one (with), associate (oneself), regard oneself as being the essence of" is from 1780. Sense of "serve as means of identification" is attested by 1886. Related: Identified; identifying.