Entry 1 sense Webster, 1913 Invalidation /ĭnˌ-vălˌ-əd-āsh'-ən/ · In·val·i·da·tion · IPA /ɪnˌvæl.əˈdeɪ.ʃən/ 01 n. The act of inavlidating, or the state of being invalidated. 1. The act of inavlidating, or the state of being invalidated. “So many invalidations of their right.” — Burke.