1590s, "short non-fiction literary composition" (first attested in writings of Francis Bacon, probably in imitation of Montaigne), from M.Fr. essai
"trial, attempt, essay," from L.L. exagium
"a weighing, weight," from L. exigere
"test," from ex-
"out" + agere
apparently meaning here "to weigh." The suggestion is of unpolished writing. The more literal verb meaning "to put to proof, test the mettle of" is from late 15c.; this sense has mostly gone with the divergent spelling assay
(q.v.). Related: Essayed
is from c.1600.