1. attempted to explain or justify (one’s or another’s behavior or attitude) with logical, plausible reasons, even if these are not true or appropriate
Usage: British spelling; past tense of rationalise
2. reorganized (a business, process, or industry) to make it more efficient and effective
Usage: British spelling; business context

Examples

• She rationalised her poor performance by blaming the difficult test questions.
• He rationalised his decision to quit by saying the job wasn’t challenging enough.
• The company rationalised its operations by closing unprofitable branches.
• They rationalised the production process to reduce costs.
• She rationalised her anger as justified concern for the project.
• The government rationalised the healthcare system to improve efficiency.