Source : Webster's Revised Unabridged Dictionary (1913)

Gnathonic \Gna*thon"ic\, Gnathonical \Gna*thon"ic*al\, a. [L.
   Gnatho, name of a parasite in the ``Eunuchus'' of Terence,
   Gr. ?; hence, a parasite in general.]
   Flattering; deceitful. [Obs.]