The Collaborative International Dictionary of English v.0.48:

Galanga \Ga*lan"ga\, Galangal \Ga*lan"gal\, n.[OE. galingale,
   OF. galingal, garingal, F. galanga (cf. Sp. galanga), prob.
   fr. Ar. khalanj[=a]n. ]
   The pungent aromatic rhizome or tuber of certain East Indian
   or Chinese species of Alpinia (Alpinia Galanga and
   Alpinia officinarum) and of the K[ae]mpferia Galanga), --
   all of the Ginger family.
   [1913 Webster]

WordNet (r) 3.0 (2006):

galangal
    n 1: southeastern Asian perennial with aromatic roots [syn:
         galangal, Alpinia galanga]
    2: European sedge having rough-edged leaves and spikelets of
       reddish flowers and aromatic roots [syn: galingale,
       galangal, Cyperus longus]