Pronunciation: (ō"vur-shad'ō),[key] —v.t. 1. to be more important or significant by comparison: For years he overshadowed his brother. 2. to cast a shadow over; cover with shadows, clouds, darkness, etc.; darken or obscure: clouds overshadowing the moon. 3. to make sad or hang heavily over; cast a pall on: a disappointment that overshadowed their last years. 4. Archaic.to shelter or protect.