Source : Webster's Revised Unabridged Dictionary (1913)

Glottis \Glot"tis\, n. [NL., fr. Gr. ?, ?, from ?, ?, the
   tongue. See {Gloss} an explanatory remark.] (Anat.)
   The opening from the pharynx into the larynx or into the
   trachea. See {Larynx}.

Source : WordNet®

glottis
     n : the vocal apparatus of the larynx; the true vocal folds and
         the space between them where the voice tone is generated
     [also: {glottides} (pl)]