acid

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Chemistry Any of a class of substances whose aqueous solutions are characterized by a sour taste, the ability to turn blue litmus red, and the ability to react with bases and certain metals to form salts.
2. n. Chemistry A substance that yields hydrogen ions when dissolved in water.
3. n. Chemistry A substance that can act as a proton donor.
4. n. Chemistry A substance that can accept a pair of electrons to form a covalent bond.
5. n. A substance having a sour taste.
6. n. The quality of being sarcastic, bitter, or scornful: wrote with acid about her first marriage.
7. n. Slang See LSD¹.
8. adj. Chemistry Of, relating to, or containing an acid.
9. adj. Chemistry Having a high concentration of acid.
10. adj. Chemistry Having the characteristics of an acid.
11. adj. Having a pH of less than 7.
12. adj. Having a relatively high concentration of hydrogen ions.
13. adj. Geology Containing a large proportion of silica: acid rocks.
14. adj. Having a sour taste. See Synonyms at sour.
15. adj. Biting, sarcastic, or scornful: an acid wit; an acid tone of voice.

Century Dictionary and Cyclopedia

1. Sour, sharp, or biting to the taste; tasting like vinegar: as, acid fruits or liquors.
2. n. Originally, a substance possessing a sour taste like that of vinegar; in modern chemical use, a name given to a large number of compounds which do not necessarily possess this property. It does not appear that very great importance was at any time attached to sourness as a characteristic of acids from a chemical point of view. The following properties are common to most acids: 1st, solubility in water; 2d, a sour taste (in some acids, on account of their corrosiveness, this property can be perceived only after dilution with a large quantity of water); 3d, the power of turning vegetable blues to red; 4th, the power of decomposing most carbonates, and displacing the carbonic acid with effervescence; 5th, the power of destroying more or less completely the characteristic properties of alkalis, at the same time losing their own distinguishing characters, forming salts. In modern chemistry an acid may be termed a salt of hydrogen, or it may be defined as a compound containing one or more atoms of hydrogen which become displaced by a metal, or by a radical possessing to a certain extent metallic functions. An acid containing one such atom of hydrogen is said to be monobasic, one containing two such atoms bibasic, etc. Acids of a greater basicity than unity are frequently termed polybasic acids. When an acid contains oxygen, its name is generally formed by adding the terminal -ic either to the name of the element with which the oxygen is united or to an abbreviation of that name. Thus, sulphur forms with oxygen sulphuric acid; nitrogen, nitric acid; and phosphorus, phosphoric acid. But it frequently happens that the same element forms two acids with oxygen; and in this case the acid that contains the larger amount of oxygen receives the terminal syllable -ic, while that containing less oxygen is made to end in -ous. Thus, we have sulphurous, nitrous, and phosphorous acid, each containing a smaller proportion of oxygen than that necessary to form respectively sulphuric, nitric, and phosphoric acid. In some instances, however, the same element forms more than two acids with oxygen, in which case the two Greek words ὑπό (hypo-), under, and ὑπέρ (hyper-), over, are prefixed to the name of the acid. Thus, an acid of sulphur containing less oxygen than sulphurous acid is termed hyposulphurous acid; and another acid of the same element containing, in proportion to sulphur, more oxygen than sulphurous acid and less than sulphuric, might be named either hypersulphurous or hyposulphuric acid; but the latter term has been adopted. The prefix per- is frequently substituted for hyper-.

Wiktionary

1. adj. Sour, sharp, or biting to the taste; tart; having the taste of vinegar.
2. adj. figuratively Sour-tempered.
3. adj. Of or pertaining to an acid; acidic.
4. adj. music Denoting a musical genre that is a distortion (as if hallucinogenic) of an existing genre, as in acid house, acid jazz, acid rock.
5. n. A sour substance.
6. n. chemistry Any of several classes of compound having the following properties:-
7. n. slang lysergic acid diethylamide

GNU Webster's 1913

1. adj. Sour, sharp, or biting to the taste; tart; having the taste of vinegar: as, acid fruits or liquors. Also fig.: Sour-tempered.
2. adj. Of or pertaining to an acid.
3. n. A sour substance.
4. n. (Chem.) One of a class of compounds, generally but not always distinguished by their sour taste, solubility in water, and reddening of vegetable blue or violet colors. They are also characterized by the power of destroying the distinctive properties of alkalies or bases, combining with them to form salts, at the same time losing their own peculiar properties. They all contain hydrogen, united with a more negative element or radical, either alone, or more generally with oxygen, and take their names from this negative element or radical. Those which contain no oxygen are sometimes called hydracids in distinction from the others which are called oxygen acids or oxacids.

WordNet 3.0

1. n. street name for lysergic acid diethylamide
2. n. any of various water-soluble compounds having a sour taste and capable of turning litmus red and reacting with a base to form a salt
3. adj. harsh or corrosive in tone
4. adj. being sour to the taste
5. adj. having the characteristics of an acid