Why is the ninth month called September?
mid-15c., "act or process of testing," from Anglo-French trial, noun formed from triet "to try" (see try). Sense of "examining and deciding a case 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 (1939) is congnate of French ballon d'essai.