The Collaborative International Dictionary of English v.0.48:

Phallus \Phal"lus\ (f[a^]l"l[u^]s), n.; pl. Phalli. [L., a
   phallus (in sense 1), Gr. fallo`s.]
   1. The emblem of the generative power in nature, carried in
      procession in the Bacchic orgies, or worshiped in various
      ways.
      [1913 Webster]

   2. (Anat.) The penis or clitoris, or the embryonic or
      primitive organ from which either may be derived.
      [1913 Webster]

   3. (Bot.) A genus of fungi which have a fetid and disgusting
      odor; the stinkhorn.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Phallus
    n 1: genus of fungi having the cap or pileus hanging free around
         the stem [syn: Phallus, genus Phallus]
    2: the male organ of copulation (`member' is a euphemism) [syn:
       penis, phallus, member]