mouse-ear hawkweed mou·seear·hawk·weed uncommon noun 1. European hawkweed having soft hairy leaves; sometimes placed in genus Hieracium Synonymsmouse-ear hawkweedPilosella officinarumHieracium pilocella Related words Broader terms hawkweed WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.