Aromatic functional groups:

An aromatic functional group is one in which an aromatic ring is straight linked to the functional group.

There is one complication including esters and amides. These functional groups are described as aromatic or aliphatic depending upon either the aryl group is directly attached to the carbonyl end of the functional group, i.e. Ar-CO-X. If the aromatic ring is linked to the heteroatom instead, after that the ester / amide is categorized as an aliphatic amide.

Figure:  (a) Aromatic ester; (b) aliphatic ester; (c) aromatic amide; (d) aliphatic amide.