1758, intransitive, "to tip or turn over;" 1769, transitive, "to turn (a vessel) over, cause to overturn, turn (anything) topsy-turvy;" a nautical word of obscure origin, perhaps (as Skeat suggests) from Spanish capuzar "to sink by the head," from cabo "head," from Latin caput "head" (from PIE root *kaput- "head"). For sense, compare French chavirer "to capsize, upset," faire capot "capsize;" Provençal cap virar "to turn the head." Related: Capsized; capsizing.
It forms all or part of: achieve; behead; biceps; cabbage; cabochon; caddie; cadet; cap; cap-a-pie; cape (n.1) "garment;" cape (n.2) "promontory;" capital (adj.); capital (n.3) "head of a column or pillar;" capitate; capitation; capitulate; capitulation; capitulum; capo (n.1) "leader of a Mafia family;" capo (n.2) "pitch-altering device for a stringed instrument;" caprice; capsize; captain; cattle; caudillo; chapter; chef; chief; chieftain; corporal (n.); decapitate; decapitation; forehead; head; hetman; kaput; kerchief; mischief; occipital; precipice; precipitate; precipitation; recapitulate; recapitulation; sinciput; triceps.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit kaput-; Latin caput "head;" Old English heafod, German Haupt, Gothic haubiþ "head."