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.
to remove unreasonable elements from.
to make rational or conformable to reason.
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.
Also especially British, ra·tion·al·ise.
Origin of rationalize
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.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
to justify (one's actions, esp discreditable actions, or beliefs) with plausible reasons, esp after the event
psychol to indulge, often unchallenged, in excuses for or explanations of (behaviour about which one feels uncomfortable or guilty)
to apply logic or reason to (something)
to eliminate unnecessary equipment, personnel, or processes from (a group of businesses, factory, etc), in order to make it more efficient
(tr) maths to eliminate one or more radicals without changing the value of (an expression) or the roots of (an equation)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Online Etymology Dictionary, © 2010 Douglas Harper
To make rational.
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.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.