Definition from Wiktionary, the free dictionary
- (organic chemistry) Either of the two isomeric carboxylic acids, normal butyric acid and isobutyric acid, with the chemical formula C3H7COOH, occurring in animal milk fat.
- (organic chemistry) Solely the straight chain isomer of the above, normal butyric acid or n-butyric acid, CH3(CH2)2COOH, a short chain fatty acid; its glyceride is one of the principle components of the flavour of butter.
Derived terms 
either of the two isomeric forms