The Collaborative International Dictionary of English v.0.48:

Erectile \E*rect"ile\, a. [Cf. F. ['e]rectile.]
   1. Capable of being erected; susceptible of being erected of
      dilated; as, erectile tissue.
      [1913 Webster]

   2. Of or pertaining to an erection[5]; as, erectile
      dysfunction.
      [PJC]

   Erectile tissue (Anat.), a tissue, such as that contained
      in the penis, which is capable of being greatly dilated
      and made rigid by accumulation of blood in and the
      consequent distension of the numerous blood vessels which
      it contains.
      [1913 Webster]

WordNet (r) 3.0 (2006):

erectile tissue
    n 1: vascular tissue capable of filling with blood and becoming
         rigid