principial
Elementary; fundamental.
On account of heat being kindled by the attrition of bodies, reject a principial nature. By principial nature I mean that which exists in the nature of things positively, and not as the effect of any antecedent nature.
Where it comes from
Probably a learned borrowing from Latin prī̆ncipiālis. By surface analysis, principia + -al.
Adapted from the Wiktionary entry principial (CC BY-SA 4.0).