Entry 1 sense Webster, 1913 Improperly /ĭmˌ-präp'-ẽrl-ē/ · Im·prop·er·ly · IPA /ɪmˈpɹɑ.pɚ.li/ 01 adv. In an improper manner; not properly; unsuitably; unbecomingly. 1. In an improper manner; not properly; unsuitably; unbecomingly.