1. to find reasons to justify or explain one’s actions or beliefs, especially when they may be wrong or unreasonable
Usage: British spelling
2. to make something more logical, efficient, or reasonable by reorganizing or restructuring it
Usage: British spelling; business context

Examples

• She rationalises her overspending by saying she deserves nice things.
• He always rationalises his mistakes instead of learning from them.
• The company rationalises its operations to reduce costs.
• Don’t try to rationalise bad behavior with weak excuses.
• The manager rationalises the workflow to improve efficiency.
• People often rationalise their fears rather than face them directly.