Entry 1 sense Webster, 1913 Inaction /ĭnˌ-ăk'-shən/ · In·ac·tion · IPA /ɪnˈækʃən/ 01 n. Lack of action or activity; forbearance from labor; idleness; rest; inertness. 1. Lack of action or activity; forbearance from labor; idleness; rest; inertness.