ˌklīstəˈthēs(h)ēəm noun
( plural cleistothe·cia -ēə)
Etymology: New Latin, from cleist- + -thecium
: a closed spore-bearing structure in ascomycetous fungi (as the Aspergillaceae and Erysiphaceae) from which the asci and spores are released only by decay or disintegration — called also cleistocarp