early 15c., "embarrassment, dread, fear," from abase + -ment. Sense of "action of lowering in price" is mid-15c.; "action of lowering in rank" is 1560s; "condition of being abased" is from 1610s.
late 14c., abaishen, from Old French abaissier "diminish, make lower in value or status" (12c.), from Vulgar Latin *ad bassiare "bring lower," from Late Latin bassus "thick, fat, low;" from the same source as base (adj.) and altered 16c. in English by influence of it, which made it an exception to the rule that Old French verbs with stem -iss- enter English as -ish. Related: Abased; abasing.