verb (used with object),ra·tion·al·ized,ra·tion·al·iz·ing.
to ascribe (one's acts, opinions, etc.) to causes that superficially seem reasonable and valid but that actually are unrelated to the true, possibly unconscious and often less creditable or agreeable causes.
Mathematics. to eliminate radicals from (an equation or expression): to rationalize the denominator of a fraction.
Chiefly British. to reorganize and integrate (an industry).
verb (used without object),ra·tion·al·ized,ra·tion·al·iz·ing.
to invent plausible explanations for acts, opinions, etc., that are actually based on other causes: He tried to prove that he was not at fault, but he was obviously rationalizing.
Although rationalize retains its principal 19th-century senses “to make conformable to reason” and “to treat in a rational manner,” 20th-century psychology has given it the now more common meaning “to ascribe (one's acts, opinions, etc.) to causes that seem reasonable but actually are unrelated to the true, possibly unconscious causes.” Although the possibility of ambiguity exists, the context will usually make clear which sense is intended.
1767, "explain in a rational way, make conformable to reason," from rational + -ize. In the psychological sense of "to give an explanation that conceals true motives" it dates from 1922. Related: Rationalized; rationalizing.
To devise self-satisfying but false or inconsistent reasons for one's behavior, especially as an unconscious defense mechanism through which irrational acts or feelings are made to appear rational to oneself.
Related formsra′tion•al•i•za′tion (-lĭ-zā′shən) n.
Michael C. Hall on Going Drag for ‘Hedwig and the Angry Inch’ and Exorcising ‘Dexter’