Webster's Revised Unabridged Dictionary · 1913

Rationalize

Rationalize (rash"un*al*īz) , transitive verb

1.
To make rational; also, to convert to rationalism.
2.
To interpret in the manner of a rationalist.
3.
To form a rational conception of.
4.
(Algebra) To render rational; to free from radical signs or quantities.

Rationalize , intransitive verb

To use, and rely on, reason in forming a theory, belief, etc., especially in matters of religion: to accord with the principles of rationalism.
Theodore... is justly considered the chief rationalizing doctor of antiquity. — J. H. Newman