compulsory: P. βίαιος, P. and V. ἀναγκαῖος.
violent: P. and V. βίαιος.
cogent: P. and V. πιθανός, P. ἀναγκαῖος (Thuc. 4, 60).
firm, strong: Met., P. ἰσχυρός.
