(biochemistry, organic chemistry) A polycyclic heterocyclic carboxylic acid, one of the vitamin B complex, essential for cell growth and reproduction

(organic chemistry) A class of organic compounds having two acyl groups bonded to the same oxygen atom. They react with water to give carboxylic acids.

(organic chemistry) Any organic compound having two carboxylic acid functional groups.

(organic chemistry) an aliphatic dicarboxylic acid, (CH₂)₆(COOH)₂, obtained from cork; used in the manufacture of plastics

(organic chemistry) A crystalline unsaturated hydroxy fatty acid C₁₈H₃₄O₃ that yields esters important as plasticizers and whose glyceride (ricinolein) is the main component of castor oil.

(chemistry) An antibacterial agent obtained from lichens of the genus Usnea.

(chemistry) the solid hydrated form of tungsten oxide, H₂WO₄; used in textiles, and in yellow glazes

(figuratively) A rigorous test or appraisal of the quality or worth of something. / (historical) In the 1960s, a party based around the use and advocacy of the psychedelic drug LSD ("acid").

(organic chemistry) Any of a class of organic compounds containing a carboxyl functional group.

(organic chemistry) 2-hydroxy-propanoic acid (CH₃.CHOH.CO₂H), a syrupy liquid, soluble in water; found in milk, wine and many fruits; used as a food additive and in many industrial applications.