Webster's Revised Unabridged Dictionary · 1913

Illative

Illative , adjective

[Latin illativus: compare French illatif.]

Relating to, dependent on, or denoting, illation; inferential; conclusive; as, an illative consequence or proposition; an illative word, as then, therefore, etc.
Collocations (2)
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 (Metaphysics) , the faculty of the mind by which it apprehends the conditions and determines upon the correctness of inferences.

Illative , noun

An illative particle, as for, because.