The Collaborative International Dictionary of English v.0.48:

Frenum \Fre"num\, n.; pl. E. Frenums, L. Frena. [L., a
   bridle.]
   1. (Zool.) A cheek stripe of color.
      [1913 Webster]

   2. (Anat.) Same as Fr[ae]num.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Fraenum \Fr[ae]"num\, or Frenum \Fre"num\, n.; pl. E.
   Fr[ae]nums, L. Fr[ae]na. [L., a bridle.] (Anat.)
   A connecting fold of membrane serving to support or restrain
   any part; as, the fr[ae]num of the tongue.
   [1913 Webster]