What is the meaning of acid?

noun

• 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.
• Street name for lysergic acid diethylamide.
  • synonyms: back breaker, battery-acid, dose, dot, Elvis, loony toons, Lucy in the sky with diamonds, pane, superman, window pane, Zen

adjective

• Harsh or corrosive in tone.
  • usage: "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"
  • synonyms: acerb, acerbic, acrid, bitter, blistering, caustic, sulfurous, sulphurous, virulent, vitriolic
• Being sour to the taste.
  • synonyms: acidic, acidulent, acidulous
• Having the characteristics of an acid.
  • usage: "an acid reaction"