1) Problem with teeth alignment 
When the lower teeth are forward of the upper teeth. This could be due to either an underdeveloped upper jaw or an overdeveloped lower jaw.
A nontechnical term applied to mandibular underdevelopment or to excessive maxillary development. ... (05 Mar 2000) ... 
Type: Term Pronunciation: ŭn′dĕr-bīt Definitions: 1. A nontechnical term applied to mandibular underdevelopment or to excessive maxillary development.
occlusion in which the lower incisor teeth overlap the upper.