The Collaborative International Dictionary of English v.0.48:

Dracontic \Dra*con"tic\, a. [From L. draco dragon, in allusion
   to the terms dragon's head and dragon's tail.] (Astron.)
   Belonging to that space of time in which the moon performs
   one revolution, from ascending node to ascending node. See
   Dragon's head, under Dragon. [Obs.] "Dracontic month."
   --Crabb.
   [1913 Webster]