Source : Webster's Revised Unabridged Dictionary (1913)

Propyl \Pro"pyl\, n. [Propionic + -yl.] (Chem.)
   The hypothetical radical {C3H7}, regarded as the essential
   residue of propane and related compounds.

Source : WordNet®

propyl
     n : the monovalent organic group C3H7- obtained from propane
         [syn: {propyl group}, {propyl radical}]