Plural ostraca. Greek name used by Egyptologists to designate flakes of limestone or pottery with ink inscriptions in hieroglyphic, hieratic, demotic, and later Greek that are often found at many sites in Egypt. Some texts may be trial pieces or school exercises, but many are complete documents that may contain literary texts or such nonliterary material as legal texts, tax documents, or letters. These often provide valuable contributions to the study of Egyptian literature and daily life, notably the thousands of ostraca found at Deir el-Medina.
Historical Dictionary Of Ancient Egypt by Morris L. Bierbrier
Ancient Egypt. A Reference Guide. EdwART. 2011.