The Collaborative International Dictionary of English v.0.48:

-yl \-yl\ [Gr. ? wood, material.] (Chem.)
   A suffix used as a characteristic termination of chemical
   radicals; as in ethyl, carbonyl, hydroxyl, etc.
   [1913 Webster]

   Note: -yl was first used in 1832 by Liebig and W["o]hler in
         naming benzoyl, in the sense of stuff, or fundamental
         material, then in 1834 by Dumas and Peligot in naming
         methyl, in the sense of wood. After this -yl was
         generally used as in benzoyl, in the sense of stuff,
         characteristic ground, fundamental material.
         [1913 Webster]