Late 14c., "pertaining to the self," from Old French personal (12c., Modern French personnel), from Late Latin personalis "pertaining to a person," from Latin persona (see person). Meaning "aimed at some particular person" (usually in a hostile manner) first attested 1610s. 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.
