The noun acid has 2 senses (first 1 from tagged texts)
1. (20) acid -- (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)
2. acid, 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)
Overview of adj acid
The adj acid has 3 senses (first 1 from tagged texts)
1. (1) acerb, acerbic, acid, acrid, bitter, blistering, caustic, sulfurous, sulphurous, venomous, virulent, vitriolic -- (harsh or corrosive in tone; "an acerbic tone piercing otherwise flowery prose"; "a barrage of acid comments"; "her acrid remarks make her many enemies"; "bitter words"; "blistering criticism"; "caustic jokes about political assassination, talk-show hosts and medical ethics"; "a sulfurous denunciation"; "a vitriolic critique")
2. acidic, acid, acidulent, acidulous -- (being sour to the taste)
3. acid -- (having the characteristics of an acid; "an acid reaction")