Dictionary:

mescal

  (mĕs-kăl') also mezcal (mĕz-kăl')

1. See peyote (sense 1).
2. 1. A Mexican liquor distilled from the fermented juice of certain species of agave.
   2. A food prepared by cooking the fleshy leaf base and trunk of certain agaves.
3. See maguey (sense 1).

[American Spanish, from Nahuatl mexcalli, mescal liquor : metl, maguey plant + perhaps ixca, xca, to bake.]

The noun has 2 meanings:

Meaning #1: a small spineless globe-shaped cactus; source of mescal buttons
  Synonyms: mezcal, peyote, Lophophora williamsii

Meaning #2: a colorless Mexican liquor distilled from fermented juices of certain desert plants of the genus Agavaceae (especially the century plant)