An Etymological Dictionary of the German Language/Annotated/glotzen
glotzen, verb, ‘to stare,’ from the equivalent Middle High German glotzen; Old High German *glozzôn, Gothic *gluttôn are wanting; compare English to gloat, Old Icelandic glotta, ‘to sneer’; perhaps primitively allied to Old Slovenian ględati, ‘to look, see.’