Latin word causa comes from Old Latin caussa (Case, claim. Cause, reason, purpose.)

Detailed word origin of causa

Dictionary entry	Language	Definition
caussa	Old Latin (itc-ola)	Case, claim. Cause, reason, purpose.
causa	Latin (lat)	For the sake of or on account of (Medieval Latin) thing. (figuratively) justification, explanation. Case, claim, contention. Cause, reason. Motive, pretext. Situation, condition.