mistrial (n.)

mid-15c., "an examination before a court" to determine guilt or innocence or the rightness of a cause; also "a trial by arms;" from Anglo-French trial, noun formed from Old French trier "to try, pick out, cull" (12c.), from Gallo-Roman *triare, a word of unknown origin. 

It is attested by late 15c. generally as "act or process of testing; a putting to proof by examination, experiment, etc." By 1540s as "state of being tried, a being subject to affliction or trouble through experience of something."

As an adjectival phrase, (rule of) 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.

prefix of Germanic origin affixed to nouns and verbs and meaning "bad, wrong," from Old English mis-, from Proto-Germanic *missa- "divergent, astray" (source also of Old Frisian and Old Saxon mis-, Middle Dutch misse-, Old High German missa-, German miß-, Old Norse mis-, Gothic missa-), perhaps literally "in a changed manner," and with a root sense of "difference, change" (compare Gothic misso "mutually"), and thus possibly from PIE *mit-to-, from root *mei- (1) "to change."

Productive as word-forming element in Old English (as in mislæran "to give bad advice, teach amiss"). In 14c.-16c. in a few verbs its sense began to be felt as "unfavorably," and it came to be used as an intensive prefix with words already expressing negative feeling (as in misdoubt). Practically a separate word in Old and early Middle English (and often written as such). Old English also had an adjective (mislic "diverse, unlike, various") and an adverb (mislice "in various directions, wrongly, astray") derived from it, corresponding to German misslich (adj.). It has become confused with mis- (2).