acid

adj

1. Sour, sharp, or biting to the taste; tart; having the taste of vinegar.

   “acid fruits or liquors”

2. (figuratively)Sour-tempered.

   “His response was harsh and acid.”

   “His voice was as stern and his face as acid as ever.”

   “It must be admitted that Challenger is provocative in the last degree, but Summerlee has an acid tongue, which makes matters worse.”

   “Little disappointed, then, she turned attention to "Chat of the Social World," gossip which exercised potent fascination upon the girl's intelligence. She devoured with more avidity than she had her food those pretentiously phrased chronicles of the snobocracy—[…]—distilling therefrom an acid envy that robbed her napoleon of all its flavor.”

3. Of or pertaining to an acid; acidic.

   “acid soils”

   “Like other nyssas, it is in nature a creature of swampy places and looks loveliest where massed close to water and reflected in it, but justifies itself elsewhere if the soil is moist and acid, succeeding in wet clay.”

4. Denoting a musical genre that is a distortion (as if hallucinogenic) of an existing genre, as in acid house, acid jazz, acid rock.

noun

1. (countable, uncountable)A sour substance.
2. (countable, uncountable)Any compound which yields H+ ions (protons) when dissolved in water; an Arrhenius acid.

   “SE onset depends on a complex network of interactions among plant growth regulators, mainly auxins and cytokinins, during the proembryogenic early stages, and ethylene and gibberellic and abscisic acids later in the development of somatic embryos.”

3. (countable, uncountable)Any compound that easily donates protons to a base; a Brønsted acid.
4. (countable, uncountable)Any compound that can accept a pair of electrons to form a covalent bond; a Lewis acid.
5. (countable, uncountable)Any corrosive substance.

   “You are in error. / This is terror. / This is your banishment. This land is mine. / This is what you earn. / This is the Law of No Return. / This is the sour dough, this the sweet wine. / This is my history, this my race / And this unhappy man threw acid in my face.”

6. (slang, uncountable)LSD, lysergic acid diethylamide.

   “In the end, though, there is one sure way to distinguish a real hippie from his assorted sympathizers: hippies drop acid. That is, real hippies frequently, if irregularly, ingest LSD.”

7. (abbreviation, acronym, alt-of, uncountable)Acronym of atomicity, consistency, isolation, and durability, a set of properties that guarantee database transactions are processed reliably.

   “SQLite relies on native file locking and page journaling to implement ACID properties.”