An organic group formed by removing one or more hydroxy groups from an oxoacid that has the general structure RkE(=O)l(OH)m (l =/= 0). Although the term is almost always applied to organic compounds, with carboxylic acid as the oxoacid, acyl groups can in principle be derived from other types of acids such as sulfonic acids or phosphonic acids.

Synonyms: alkanoyl acyl group