gam·ma-a·mi·no·bu·tyr·ic acid 
(găm′ə-ə-mē′nō-by-tîrĭk, -ăm′ə-)
(găm′ə-ə-mē′nō-by-tîrĭk, -ăm′ə-)n. Abbr. GABA
An amino acid, C4H9NO2, that is not found in proteins, but occurs in the central nervous system and is associated with the transmission of nerve impulses.