What's the "een" in Halloween?
1580s, apparently short for obsolete capriole "to leap, skip," probably from Italian capriolare "jump in the air" (see cab). Related: Capered; capering.
type of prickly Mediterranean bush, also in reference to the plant's edible buds, late 14c., from Latin capparis (source of Italian cappero, French câpre, German Kaper), from Greek kapparis "the caper plant or its fruit," of uncertain origin. Arabic kabbar, Persian kabar are from Greek. Perhaps reborrowed into English 16c. The final -s was mistaken for a plural inflection in English and dropped.
by 1590s, "playful leap or jump," from caper (v.); meaning "prank" is from 1840; that of "crime" is from 1926. To cut capers "dance in a frolicsome way" is from c.1600.