bipenniform--prophetes.ai

bipenniform, a.
  (baɪˈpɛnɪfɔːm)
  [f. bi- prefix 1 + penniform.]
  Feather-shaped on both sides.

1842 E. Wilson Anat. Vade M. 136 Or bipenniform, converging to both sides of the tendon.

Oxford English Dictionary