[医] 底, 基底

Basi- \Ba"si-\
A combining form, especially in anatomical and botanical
words, to indicate the base or position at or near a base;
forming a base; as, basibranchials, the most ventral of the
cartilages or bones of the branchial arches; basicranial,
situated at the base of the cranium; basifacial,
basitemporal, etc.