Entry 1 sense Webster, 1913 Nacreous /(nā"krē̇*ŭs)/ · Na·cre·ous · IPA /ˈneɪ.kɹi.əs/ 01 a. Consisting of, or resembling, nacre; pearly. 1. Consisting of, or resembling, nacre; pearly.(Zool.)