The Collaborative International Dictionary of English v.0.48:

Hallux \Hal"lux\ (h[a^]l"l[u^]ks), n. [NL., fr. L. hallex,
   allex.] (Anat.)
   The first, or preaxial, digit of the hind limb, corresponding
   to the pollux in the fore limb; the great toe; the hind toe
   of birds.
   [1913 Webster]

WordNet (r) 3.0 (2006):

hallux
    n 1: the first largest innermost toe [syn: big toe, great
         toe, hallux]