(Chapter ad) Footnote 15:

os basillare; in English, “basilar” means pertaining to the base, particularly of the skull. In modern anatomy the basilaris cranii is “a composite of the numerous bones which serve as a supportive floor and form the axis of the whole skull” ( Dorland’s, 1994). Vesalius’ explanation may be an attempt to link the work with Gk. basilikos, “royal” because it makes up “a large portion of the head.” The Latin term is not given in OLD.