carboxyl group

noun
1.
the univalent radical COOH, present in and characteristic of organic acids.
Origin
1875-80
British Dictionary definitions for carboxyl group

carboxyl group

/kɑːˈbɒksaɪl; -sɪl/
noun
1.
the monovalent group –COOH, consisting of a carbonyl group bound to a hydroxyl group: the functional group in organic acids
Word Origin
C19 carboxyl, from carbo- + oxy-² + -yl