Rationalization refers to a defense mechanism that involves reinterpreting our Behavior to make it more acceptable and less threatening to us.
Rationalization means creating false but pla
usible excuses to justify unacceptable behavior. Individuals can provide a plausible but inaccurate explanation for their failures. An individual who blames her roommate for her own poor performance on an examination may be making excuses for her lack of study and thus rationalizing.
Other /More definition:
Rationalization refers to the cognitive reframing of ones perceptions to protect the ego in the face of changing realities. It is creating logical explanations that make the cause of an event sound acceptable. One way of rationalizing is to point to external causes and, therefore, protect one's self from blame.