Isobutyr

Part of speech: noun

Definitions

1. A chemical prefix denoting a branched four-carbon group, used in the names of compounds derived from a branched-chain fatty acid and its salts and esters
2. Relating to a branched-chain four-carbon acid or to the salts and esters formed from such an acid in organic chemistry
3. Used in chemical names to mark a four-carbon branched structure, as in the naming of certain fatty acids and their derivatives

Etymology: Its core is the Greek "boutyron," literally "cow-cheese," from "bous" (cow) and "tyros" (cheese), which gave Latin "butyrum" and English "butter." Chemists used that root for butyric acid, the compound responsible for the sharp smell of rancid butter. The "iso-" comes from Greek "isos," meaning "equal" or "same." In organic chemistry it marks an isomer, a compound with the same atoms arranged differently. Isobutyric acid has four carbon atoms like butyric acid, but they form a branched chain rather than a straight one.