late 14c., "reduce in rank, etc.," from Old French abaissier "diminish, make lower in value or status; lower oneself" (12c.), literally "bend, lean down," from Vulgar Latin *ad bassiare "bring lower," from ad "to, toward" (see ad-) + Late Latin bassus "low, short" (see base (adj.)).

The form in English was altered 16c. by influence of base (adj.), making the word an exception to the rule that Old French verbs with stem -iss- enter English as -ish (comprehension might have played a role; earlier forms of abase often are identical with those of abash). Literal sense of "lower, depress" (late 15c.) is archaic or obsolete. Related: Abased; abasing.

early 13c. (intransitive) "to bubble up, be in a state of ebullition," especially from heat, from Old French bolir "boil, bubble up, ferment, gush" (12c., Modern French bouillir), from Latin bullire "to bubble, seethe," from PIE *beu- "to swell" (see bull (n.2)). The native word is seethe. The figurative sense, of passions, feelings, etc., "be in an agitated state" is from 1640s.

I am impatient, and my blood boyls high. [Thomas Otway, "Alcibiades," 1675]

The transitive sense "put into a boiling condition, cause to boil" is from early 14c. The noun is from mid-15c. as "an act of boiling," 1813 as "state of boiling." Related: Boiled; boiling. Boiling point "temperature at which a liquid is converted into vapor" is recorded from 1773.