boil (v.) Look up boil at Dictionary.com
early 13c., from Old French bolir "boil, bubble up, ferment, gush" (12c., Modern French bouillir), from Latin bullire "to bubble, seethe," from PIE base *beu- "to swell" (see bull (n.2)). The native word is seethe. Figurative sense of "to agitate the feelings" is from 1640s.
I am impatient, and my blood boyls high. [Thomas Otway, "Alcibiades," 1675]
Related: Boiled; boiling. Boiling point is recorded from 1773.
boil (n.) Look up boil at Dictionary.com
"hard tumor," altered from Middle English bile (Kentish bele), perhaps by association with the verb; from Old English byl, byle "boil, carbuncle," from West Germanic *buljon- "swelling" (cognates: Old Frisian bele, Old High German bulia, German Beule). Perhaps ultimately from PIE root *bhel- (2) "to swell" (see bole), or from *beu- "to grow, swell" (see bull (n.2); also compare boast (n.)). Compare Old Irish bolach "pustule," Gothic ufbauljan "to puff up," Icelandic beyla "hump."