The Collaborative International Dictionary of English v.0.48:

Meth \Meth\, n.
   See Meathe. [Obs.] --Chaucer.
   [1913 Webster]

WordNet (r) 3.0 (2006):

meth
    n 1: an amphetamine derivative (trade name Methedrine) used in
         the form of a crystalline hydrochloride; used as a
         stimulant to the nervous system and as an appetite
         suppressant [syn: methamphetamine, methamphetamine
         hydrochloride, Methedrine, meth, deoxyephedrine,
         chalk, chicken feed, crank, glass, ice, shabu,
         trash]