grossly UK /ˈɡɹəʊsli/US /ˈɡɹoʊsli/ adverb4 •Greatly; to a large degree, especially one large enough to be frankly appreciable. •To a serious, severe, or offensive degree. •(informal) In a gross (disgusting) manner; without delicacy.The men were talking grossly about their sexual conquests. •(no longer used) Roughly; approximately; inexactly; sketchily.