"of or pertaining to the period before a trial," 1921, American English, from pre- "before" + trial. As a noun, "preliminary hearing before a trial," 1938.
Entries linking to pretrial
pre-
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-.
trial n.
mid-15c., "act or process of testing, a putting to proof by examination, experiment, etc.," from Anglo-French trial, noun formed from trier "to try" (see try (v.)). Sense of "examining and deciding of the issues between parties in a court of law" is first recorded 1570s; extended to any ordeal by 1590s.
As an adjectival phrase, trial-and-error is recorded from 1806. Trial balloon (1826) translates French ballon d'essai, a small balloon sent up immediately before a manned ascent to determine the direction and tendency of winds in the upper air, though the earliest use in English is figurative.