The Collaborative International Dictionary of English v.0.48:

Mezcal \Mez*cal"\, n.
   Same as Mescal.
   [1913 Webster]

WordNet (r) 3.0 (2006):

mezcal
    n 1: a small spineless globe-shaped cactus; source of mescal
         buttons [syn: mescal, mezcal, peyote, Lophophora
         williamsii]