Webster’s 1913 has no entry under this spelling.
Shades of meaning
Fernald has no entry of its own for final cause; he lists it under design.
Where he writes about it:
While the cause of any event, act, or fact, as commonly understood, is the power that makes it to be, the reason of or for it is the explanation given by the human mind; but reason is, in popular language, often used as equivalent to cause, especially in the sense of final cause. — from reason