Etymology
Advertisement
capsize (v.)

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.

Related entries & more 
Advertisement
*kaput- 
Proto-Indo-European root meaning "head."

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."
Related entries & more 
overset (n.)

"an overturn, ruin," mid-15c., from over- + set (v.). The verb, "to turn over, cause to capsize," is from 1590s; earlier it meant "to oppress" (c. 1200), "to overpower" (late 14c.). Related: Overset; oversetting.

Related entries & more 
keel (v.1)
of a ship, "turn keel-up" (intransitive), 1828, from keel (n.). To keel over is to "capsize" (1829), hence generally "tumble, fall" (1833), from the nautical image of a ship turning keel-up, an extended sense first in sporting, in reference to shot game. Related: Keeled; keeling.
Related entries & more 
upset (v.)
mid-15c., "to set up, fix," from up (adv.) + set (v.). Similar formation in Middle Dutch opsetten "set up, propose," German aufsetzen. Modern sense of "overturn, capsize" (1803) is that of obsolete overset. In reference to the stomach, from 1834. Meaning "to throw into mental discomposure" is from 1805. Related: Upsetting.
Related entries & more 
Advertisement