experience:  Experience, experiment , and expert  all come from the same source, Latin experīrī. This was a compound verb formed from the prefix ex- ‘out’ and a prehistoric base *per- denoting ‘attempt, trial’ (found also in English empirical, peril, pirate, and repertory), and meant ‘try, test’. The original meaning is best preserved in experiment, but in fact experience too meant at first ‘putting to the test’ in English.
From this developed the notion of ‘actually observing phenomena in order to gain knowledge of them’, which in turn led to the more subjective ‘condition of having undergone or been affected by a particular event’. The sense ‘knowledge or skill gained from such observation or from undergoing such events’ did not, however, emerge until the late 15th century. Expert was originally only an adjective, meaning ‘having experience of something’, or ‘trained by such experience’; its use as a noun only developed in the 19th century. => empirical, experiment, expert, peril, pirate, repertory
late 14c., "observation as the source of knowledge; actual observation; an event which has affected one," from Old French esperience "experiment, proof, experience" (13c.), from Latin experientia "a trial, proof, experiment; knowledge gained by repeated trials," from experientem (nominative experiens) "experienced, enterprising, active, industrious," present participle of experiri "to try, test," from ex- "out of" (see ex-) + peritus "experienced, tested," from PIE root *per- (3) "to lead, pass over" (see peril). Meaning "state of having done something and gotten handy at it" is from late 15c.