Aryl

An organic group derived from an aromatic hydrocarbon by removal of one hydrogen.

In the context of organic molecules, aryl refers to any functional group or substituent derived from a simple aromatic ring, be it phenyl, thiophene, indolyl, etc (see IUPAC nomenclature) . "Aryl" is used for the sake of abbreviation or generalization.

A simple aryl group is phenyl, C6H5; it is derived from benzene. The tolyl group, CH3C6H4, is derived from toluene (methylbenzene). The xylyl group, (CH3)2C6H3, is derived from xylene (dimethylbenzene).

Aryl Group on Wiki:
http://en.wikipedia.org/wiki/Aryl

Aryl Group on IUPAC Gold Book:
http://goldbook.iupac.org/A00464.html