<p><strong>Verb</strong></p><ul><li>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.</li><li>to remove unreasonable elements from.</li><li>to make rational or conformable to reason.</li><li>to treat or explain in a rational or rationalistic manner.</li><li>to eliminate radicals from (an equation or expression): to rationalize the denominator of a fraction.</li><li>to reorganize and integrate (an industry).</li></ul><p><strong>Verb (used without object)</strong></p><ul><li>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.</li><li>to employ reason; think in a rational or rationalistic manner.</li></ul>