Sub·gla'cial adjective Pertaining or belonging to the under side of a glacier; being beneath a glacier; as, subglacial streams. Found on http://www.encyclo.co.uk/webster/S/222
subglacial 1. Pertaining or belonging to the under side of a glacier. 2. Being beneath a glacier; such as, subglacial streams. 2. Formerly beneath a glacier; as, a subglacial deposit. Found on http://www.wordinfo.info/words/index/info/view_unit/913/2