CARBOXYL

carboxyl, carboxylic

(adjective) relating to or containing the carboxyl group or carboxyl radical

carboxyl, carboxyl group

(noun) the univalent radical -COOH; present in and characteristic of organic acids

Source: WordNet® 3.1

Noun

carboxyl (plural carboxyls)

(organic chemistry) A univalent functional group consisting of a carbonyl and a hydroxyl functional group (-CO.OH); characteristic of carboxylic acids.

Source: Wiktionary

Car*box"yl, n. Etym: [Carbon + oxygen + -yl.] (Chem.)

Definition: The complex radical, CO.OH, regarded as the essential and characteristic constituent which all oxygen acids of carbon (as formic, acetic, benzoic acids, etc.) have in common; -- called also oxatyl.

Source: Webster’s Unabridged Dictionary 1913 Edition