dull (adj.)youdaoicibaDictYouDict[dull 词源字典]
c. 1200, "stupid;" early 13c., "blunt, not sharp;" rare before mid-14c., apparently from Old English dol "dull-witted, foolish," or an unrecorded parallel word, or from Middle Low German dul "slow-witted," both from Proto-Germanic *dulaz (cognates: Old Frisian and Old Saxon dol "foolish," Old High German tol, German toll "mad, wild," Gothic dwals "foolish"), from PIE *dheu- (1) "dust, vapor, smoke" (and related notions of "defective perception or wits"). Of color from early 15c.; of pain or other sensations from 1725. Sense of "boring" first recorded 1580s.
dull. (8) Not exhilarating; not delightful; as to make dictionaries is dull work. [Johnson]
Dullsville, slang for "town where nothing happens," attested from 1960.[dull etymology, dull origin, 英语词源]
exhilarate (v.)youdaoicibaDictYouDict
1530s, from Latin exhilaratus "cheerful, merry," past participle of exhilarare "gladden, cheer," from ex- "thoroughly" (see ex-) + hilarare "make cheerful," from hilarus "cheerful" (see hilarity). Related: Exhilarated; exhilarating.
laughing (n.)youdaoicibaDictYouDict
mid-14c., verbal noun from laugh (v.). Laughing matter (usually with negative) is from 1560s. Nitrous oxide has been called laughing gas since 1842 (for its exhilarating effects). Davy, experimenting with the gas, discovered these as far back as 1779: "When I took the bag from my mouth, I immediately laughed. The laughter was involuntary, but highly pleasurable, accompanied by a thrill all through me."