Source : Webster's Revised Unabridged Dictionary (1913)

Macroglossia \Mac`ro*glos"si*a\, n. [NL. See {Macro-}, and
   {Glossa}.] (Med.)
   Enlargement or hypertrophy of the tongue.

Source : WordNet®

macroglossia
     n : a congenital disorder characterized by an abnormally large
         tongue; often seen in cases of Down's syndrome