definition of
acid

[1] #1 acid 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. wn

[2] #2 acid n. [back breaker, battery-acid, dose, dot, Elvis, loony toons, Lucy in the sky with diamonds, pane, superman, window pane, Zen] street name for lysergic acid diethylamide. wn

[3] #3 acid s. [acidic, acidulent, acidulous] being sour to the taste. wn

[4] #4 acid s. having the characteristics of an acid; "an acid reaction". wn