[ per-ee-os-truh-kuh m ]
/ ˌpɛr iˈɒs trə kəm /

noun, plural per·i·os·tra·ca [per-ee-os-truh-kuh] /ˌpɛr iˈɒs trə kə/.

the external, chitinlike covering of the shell of certain mollusks that protects the limy portion from acids.

Origin of periostracum

1830–40; < New Latin, equivalent to peri- peri- + ostracum a shell < Greek óstrakon. See oyster

OTHER WORDS FROM periostracum

per·i·os·tra·cal, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Examples from the Web for periostracum

  • Gray calls it the Periostracum, from the membranous skin covering the bones of quadrupeds.

    A Conchological Manual|George Brettingham Sowerby
  • The periostracum, or epidermis, is heavy and often velvety or even hairy.

    The Sea-beach at Ebb-tide|Augusta Foote Arnold