R-CO-

Acyl Ac"yl, n. [Acid + -yl.] (Org. Chem.) An acid radical, as acetyl, malonyl, or benzoyl. An acyl radical can be depicted as {R-CO-}, where {-CO-} is the carbonyl group, and R is the group that characterizes the acyl moiety. [Webster 1913 Suppl. +PJC] ||