ac´id|ly

ac|id «AS ihd», noun, adjective.

–n.

1. a) a chemical compound with a sour or bitter taste that usually unites with a base to form a salt. Acids have a pH value of less than 7. They change blue litmus paper to red and yield hydrogen ions in a water solution. Hydrochloric acid and sulfuric acid are two common kinds. »

Certain bacteria cause some foods to form acids that eat their way slowly through the enamel of the teeth.

b) any ionic or molecular substance which can give up a proton. c) any molecule or ion that can attach itself to a pair of electrons from a base, forming a covalent bond. d) substance with a sour taste like that of vinegar.

2. Slang. LSD (lysergic acid diethylamide), a hallucinogen: »

The hippies say there is not much acid (LSD) around now, but that grass (marijuana) is plentiful (New York Times).

–adj.

1. of acids; having the properties of an acid: »

Blue litmus paper turns red in an acid solution.

2. sharp or biting to the taste; sour: »

Lemons are an acid fruit.

SYNONYM(S): tart. See syn. under sour. (Cf. ↑sour)

3. Figurative. sharp in manner or temper; caustic: »

an acid tongue. Mother made an acid comment about my disorderly room.

4. containing a large proportion of silica; acidic: »

Granite is an acid rock.

5. containing more acid than is normal.

6. having a pH factor of less than 7; having a relatively high concentration of hydrogen ions (contrasted with alkaline especially as a characteristic of soil).

╂[< Latin acidus sour < acēre be sour]

–ac´id|ly, adverb.

–ac´id|ness, noun.