The Collaborative International Dictionary of English v.0.48:

Linga \Lin"ga\ (l[i^][ng]"g[.a]), Lingam \Lin"gam\
   (l[i^][ng]"g[a^]m), n. [Skr. li[.n]ga.]
   The phallic symbol under which Siva is principally worshiped
   in his character of the creative and reproductive power.
   --Whitworth. E. Arnold.
   [1913 Webster]

WordNet (r) 3.0 (2006):

lingam
    n 1: the Hindu phallic symbol of Siva