Entry 1 sense Webster, 1913 Observational /äbˌ-zẽrv-āsh'-ən-əl/ · Ob·ser·va·tion·al · IPA /ˌɑbzɚˈveɪʃənəl/ 01 a. Of or pertaining to observation; consisting of, or containing, observations. 1. Of or pertaining to observation; consisting of, or containing, observations.