Nacre (nāk&etilde_;r), n. [F., cf. Sp. nácara, nácar, It. nacchera, naccaro, LL. nacara, nacrum; of Oriental origin, cf. Ar. nakīr hollowed.] (Zoöl.) A pearly substance which lines the interior of many shells, and is most perfect in the mother-of-pearl. [Written also nacker and naker.] See Pearl, and Mother-of-pearl.[1913 Webster]