"lodging for ships; sheltered recess in a coastline," early 12c., a specialized sense of Middle English herberwe "temporary dwelling place, quarters, lodgings; an inn; the camp of an army in the field," probably from Old English here-beorg (West Saxon), *here-berg (Anglian) "lodgings, quarters," from Proto-Germanic compound *harja-bergaz "shelter, lodgings," from *heri "army, host" (see harry (v.)) + *burzjan- "protection, shelter" (from PIE root *bhergh- (1) "to hide, protect"). Perhaps modeled on Old Norse herbergi "room, lodgings, quarters."
c. 1300, non-glandular organ of the abdomen, from Old French esplen, from Latin splen, from Greek splen "the milt, spleen," from PIE *spelgh- "spleen, milt" (source also of Sanskrit plihan-, Avestan sperezan, Armenian p'aicaln, Latin lien, Old Church Slavonic slezena, Lithuanian blužnis, Old Prussian blusne, Old Irish selg "spleen").
Regarded in old medicine as the seat of morose feelings and bad temper. Hence figurative sense of "violent ill-temper" (1580s, implied in spleenful); and thence spleenless "free from anger, ill-humor, malice, or spite" (1610s).
late 14c., "emit from a confined space," probably a shortening of aventer "expose oneself to the air" (c. 1300), from Old French eventer "let out, expose to air," from Vulgar Latin *exventare, from Latin ex "out" + ventus "wind" (from PIE *wē-nt-o‑ "blowing," suffixed (participial) form of root *we- "to blow").
Sense of "express freely" first recorded 1590s. Sense of "divulge, publish" (1590s) is behind phrase vent one's spleen (see spleen). Related: Vented; venting.