Main Entry: pe·num·bra

Pronunciation: \pə-ˈnəm-brə\

Function: noun

Inflected Form(s): plural pe·num·brae \-(ˌ)brē, -ˌbrī\ or pe·num·bras

: a blurred area in a radiograph at the edge of an anatomical structure

—pe·num·bral \-brəl\ adjective