boilyoudaoicibaDictYouDict[boil 词源字典]
boil: Boil ‘large spot’ [OE] and boil ‘vaporize with heat’ [13] are distinct words. The former comes from Old English byl or byle, which became bile in Middle English; the change to boil started in the 15th century, perhaps from association with the verb. The Old English word goes back ultimately to a West Germanic *būlja, whose central meaning element was ‘swelling’; from it also comes German beule ‘lump, boil’.

The verb’s source, via Anglo-Norman boiller, is Latin bullīre, a derivative of bulla ‘bubble’, a word which also gave us bull (as in ‘Papal bull’), bullion, bowl (as in the game of ‘bowls’), budge, bullet, bulletin and bully (as in ‘bully beef’), as well, perhaps, as bill.
=> bill, bowl, budge, bull, bullet, bulletin, bullion, bully, ebullient[boil etymology, boil origin, 英语词源]
boil (v.)youdaoicibaDictYouDict
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.)youdaoicibaDictYouDict
"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."