The Collaborative International Dictionary of English v.0.48:

Benzyl \Ben"zyl\, n. [Benzoic + -yl.] (Chem.)
   A compound radical, C6H5.CH2, related to toluene and
   benzoic acid; -- commonly used adjectively.
   [1913 Webster]

WordNet (r) 3.0 (2006):

benzyl
    n 1: the univalent radical derived from toluene [syn: benzyl,
         benzyl group, benzyl radical]