1610s, "skilled in a particular art or subject," formed in English from technic + -al (1), or in part from Latinized form of Greek tekhnikos "of art; systematic," in reference to persons "skillful, artistic," from tekhnē "art, skill, craft" (see techno-).
The sense narrowed to "having to do with the mechanical arts" (1727). The basketball technical foul (one which does not involve contact between opponents) is recorded from 1934. The boxing technical knock-out (one in which the loser is not knocked out) is recorded from 1921; abbreviation TKO is from 1940s. Technical difficulty is from 1805.