Entry 1 sense Webster, 1913 Misbehavior /mĭsˌ-bəh-āv'-yẽr/ · Mis·be·hav·ior · IPA /ˌmɪsbɪˈheɪvjɚ/ 01 n. Improper, rude, or uncivil behavior; ill conduct. 1. Improper, rude, or uncivil behavior; ill conduct.