Il·la·tive a. Relating to, dependent on, or denoting, illation; inferential; conclusive; as, an illative consequence or proposition; an illative word, as then, therefore, etc.
Illative conversion Logic, a converse or reverse statement of a proposition which in that form must be true because the original proposition is true.
Illative sense Metaph., the faculty of the mind by which it apprehends the conditions and determines upon the correctness of inferences.