acidyoudaoicibaDictYouDict[acid 词源字典]
acid: [17] The original notion contained in the word acid is ‘pointedness’. In common with a wide range of other English words (for example acute, acne, edge, oxygen) it can be traced back ultimately to the Indo-European base *ak-, which meant ‘be pointed or sharp’. Among the Latin derivatives of this base was the adjective ācer ‘sharp’.

From this was formed the verb acere ‘be sharp or sour’, and from this verb in turn the adjective acidus ‘sour’. The scientist Francis Bacon seems to have been the first to introduce it into English, in the early 17th century (though whether directly from Latin or from French acide is not clear). Its use as a noun, in the strict technical sense of a class of substances that react with alkalis or bases, developed during the 18th century.
=> acacia, acne, acrid, acute, alacrity, ear, edge, oxygen[acid etymology, acid origin, 英语词源]
acid (adj.)youdaoicibaDictYouDict
1620s, "of the taste of vinegar," from French acide (16c.) or directly from Latin acidus "sour, sharp," adjective of state from acere "to be sour," from PIE root *ak- "sharp, pointed" (see acrid). Figurative use from 1775; applied to intense colors from 1916. Acid test is American English, 1892, from the frontier days, when gold was distinguished from similar metals by application of nitric acid. Acid rain is first recorded 1859 in reference to England.
acid (n.)youdaoicibaDictYouDict
1690s, from acid (adj.). Slang meaning "LSD-25" first recorded 1966 (see LSD).
When I was on acid I would see things that looked like beams of light, and I would hear things that sounded an awful lot like car horns. [Mitch Hedberg, 1968-2005, U.S. stand-up comic]
Acid rock (type played by or listen to by people using LSD) is also from 1966; acid house dance music style is 1988, probably from acid in the hallucinogenic sense + house "dance club DJ music style."