The Collaborative International Dictionary of English v.0.48:

Elephantine \El`e*phan"tine\, a. [L. elephantinus of ivory, Gr.
   ?: cf. F. ['e]l['e]phantin.]
   Pertaining to the elephant, or resembling an elephant
   (commonly, in size); hence, huge; immense; heavy; as, of
   elephantine proportions; an elephantine step or tread.
   [1913 Webster]

   Elephantine epoch (Geol.), the epoch distinguished by the
      existence of large pachyderms. --Mantell.

   Elephantine tortoise (Zo["o]l.), a huge land tortoise;
      esp., Testudo elephantina, from islands in the Indian
      Ocean; and T. elephantopus, from the Galapagos Islands.
      Elephantoid