Entry 1 sense Webster, 1913 Idealistic /īd-ēˌ-əl-ĭs'-tĭk/ · I·de·al·is·tic · IPA /aɪdˌiːəlˈɪstɪk/ 01 a. Of or pertaining to idealists or their theories. 1. Of or pertaining to idealists or their theories.