illative, a. [L. illativus: cf. F. illatif.].
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.
Relating to, dependent on, or denoting, illation; inferential; conclusive; as, an illative consequence or proposition; an illative word, as then, therefore, etc. [1913 Webster]