preterm (adj.)

c. 1200, terme, "a limit in time, set or appointed period; the duration of life, lifespan;" from Old French terme "limit of time or place, date, appointed time, duration" (11c.), from Latin terminus "end, boundary line," in Medieval Latin "expression, definition," related to termen "boundary, end" (see terminus). Old English had termen "term, end," from Latin.

The sense of "period of time during which something happens" is by c. 1300, especially in reference to a stated period during which a court of justice may hold sessions (early 15c.) or during which instruction is offered at a school or university (mid-15c.). Term-paper in U.S. educational sense is recorded from 1931.

The meaning "word or phrase used in a limited or precise sense" is recorded from late 14c., from Medieval Latin use (Boethius) of terminus to render Greek horos "boundary" as it was employed in logic and mathematics (the terms of a line are its points). Hence in terms of "in the language or phraseology peculiar to" (1743, originally in reference to mathematics).

As "end of one's life," early 14c.; as "end of a medical process or operation," early 15c. The meaning "completion of the period of pregnancy" is attested from 1844.

word-forming element meaning "before," from Old French pre- and Medieval Latin pre-, both from Latin prae (adverb and preposition) "before in time or place," from PIE *peri- (source also of Oscan prai, Umbrian pre, Sanskrit pare "thereupon," Greek parai "at," Gaulish are- "at, before," Lithuanian prie "at," Old Church Slavonic pri "at," Gothic faura, Old English fore "before"), extended form of root *per- (1) "forward," hence "beyond, in front of, before."

The Latin word was active in forming verbs. Also see prae-. Sometimes in Middle English muddled with words in pro- or per-.