The Collaborative International Dictionary of English v.0.48:

Formyl \For"myl\, n. [Formic + -yl.] (Chem.)
   (a) A univalent radical, H.C:O, regarded as the essential
       residue of formic acid and aldehyde.
   (b) Formerly, the radical methyl, CH3.
       [1913 Webster]