Entry 2 senses Webster, 1913 Perfectionism /pẽrf-ĕk'-shən-ĭzˌ-əm/ · Per·fec·tion·ism · IPA /pɚˈfɛk.ʃə.nɪ.zm̩/ 01 n. The doctrine of the Perfectionists. 1. The doctrine of the Perfectionists. 2. A personal attitude which demands perfection in the results of actions.