Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† ostrăcĭas, ae, m., and ostrăcītis, ĭdis, f., = οστρακίας, ὀστρακῖτις, a semigem, prob. hornstone or chalcedony, Plin. 37, 10, 65, § 177.