Etymology
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acid (n.)

1690s, from acid (adj.); originally loosely applied to any substance tasting like vinegar, in modern chemistry gradually given more precise definitions from early 18c. 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 performed or received 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."

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acid (adj.)

1620s, "of the taste of vinegar," from French acide (16c.) or directly from Latin acidus "sour, sharp, tart" (also figurative, "disagreeable," etc.), adjective of state from acere "to be sour, be sharp" (from PIE root *ak- "be sharp, rise (out) to a point, pierce").

Figurative use in English is from 1775; applied to intense colors from 1916; an acid dye (1888) involves an acid bath. Acid rain "highly acidity in rain caused by atmospheric pollution" is recorded by 1859 in reference to England. Acid drop as a kind of hard sugar candy flavored with tartaric acid is by 1835, with drop (n.) in the "lozenge" sense. Acid test is American English, 1881, in literal use a quick way to distinguish gold from similar metals by application of nitric acid. Fowler wrote (1920) that it was then in vogue in the figurative sense and "became familiar through a conspicuous use of it during the war by President Wilson."

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glutamate (n.)
salt of glutamic acid, 1876, from glutamic acid (see gluten) + -ate (3).
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nitric (adj.)

"of, pertaining to, or derived from nitre," 1794, originally in reference to acid obtained initially from distillation of saltpeter; see nitre + -ic. Perhaps immediately from French nitrique. The acid was known as aqua fortis, later acid spirit of nitre, then nitric acid (1787) under the system ordered by Lavoisier.

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deoxyribonucleic (n.)

1931, in deoxyribonucleic acid (originally desoxyribonucleic), a nucleic acid which yields deoxyribose on hydrolysis, from deoxyribose (q.v.) + nucleic acid (see nucleic). It is generally found in chromosomes of higher organisms and stores genetic information.

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acidophilus (adj.)
1920, used of milk fermented by acidophilic bacteria, from acidophil (1900), indicating "easily stained by acid dyes," a hybrid word, from Latin acidus "acidic, sour, tart" (see acid (adj.)) + Greek philos "loving" (see -phile); the bacteria so called because they stain easily with an acid dye.
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carbonate (n.)
"compound formed by the union of carbonic acid with a base," 1794, from French carbonate "salt of carbonic acid" (Lavoisier), from Modern Latin carbonatem "a carbonated (substance)," from Latin carbo (see carbon).
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acidic (adj.)
1877, originally in geology; see acid (n.) + -ic.
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thymine (n.)
nitrogenous base, 1894, from German (Kossel and Neumann, 1893), from thymic acid, from which it was isolated, the acid so called because obtained from the thymus gland. With chemical suffix -ine (2).
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RNA (n.)
1948, abbreviation of ribonucleic acid (see ribonucleic).
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