formyl--prophetes.ai

formyl Chem.
  (ˈfɔːmɪl)
  [f. form- + -yl.]
  The hypothetical radical (CHO) of formic acid.

1879 Cassell's Techn. Educ. IV. 118/2 Formyle is the hypothetical radical of formic acid, first discovered in the red ant.

Oxford English Dictionary