A form of microstomia in which the oral opening is a small vertical slit. ... Origin: hypo-+ G. Stoma, mouth ... (05 Mar 2000) ... 
(hi″po-sto´me-ә) a developmental anomaly characterized by abnormal smallness of the mouth, the slit being vertical instead of horizontal.
Type: Term Pronunciation: hī′pō-stō′mē-ă Definitions: 1. A form of microstomia in which the oral opening is a small vertical slit.