Source : Webster's Revised Unabridged Dictionary (1913)

Eucalyn \Eu"ca*lyn\ ([=u]"k[.a]*l[i^]n), n. (Chem.)
   An unfermentable sugar, obtained as an uncrystallizable sirup
   by the decomposition of melitose; also obtained from a
   Tasmanian {eucalyptus}, -- whence its name.