os calcis
/ˌɒs ˈkalkɪs/ /ˌɒs ˈkalsɪs/Anatomy and Zoology
noun
The heel bone (calcaneus).
Origin
Mid 17th century; earliest use found in Alexander Read (1586?–1641). From classical Latin os calcis (Celsus) from os + calcis, genitive of calx, back part of the foot, heel.