The Collaborative International Dictionary of English v.0.48:

Nacre \Na"cre\ (n[=a]"k[~e]r), n. [F., cf. Sp. n['a]cara,
   n['a]car, It. nacchera, naccaro, LL. nacara, nacrum; of
   Oriental origin, cf. Ar. nak[imac]r hollowed.] (Zool.)
   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]

The Collaborative International Dictionary of English v.0.48:

Nacr'e \Na`cr['e]"\ (n[.a]*kr[=a]"), a. [F. See Nacre.] (Art)
   Having the peculiar iridescence of nacre, or mother-of-pearl,
   or an iridescence resembling it; as, nacr['e] ware.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

nacre
    n 1: the iridescent internal layer of a mollusk shell [syn:
         mother-of-pearl, nacre]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "nacre":
   Dalmatian, antigorite, butterfly, candy cane, chameleon, cheetah,
   chrysotile, confetti, crazy quilt, firedog, harlequin, iridescence,
   iris, jaguar, leopard, mackerel, mackerel sky, marble,
   marbled paper, moire, mother-of-pearl, mother-of-pearl cloud,
   nacreousness, ocelot, opal, opalescence, ophite, patchwork quilt,
   peacock, pearliness, rainbow, serpentine, serpentine marble,
   shot silk, spectrum, tortoise shell, zebra