1. attempting to explain or justify behavior or an attitude with logical reasons, even if these are not appropriate
Usage: British spelling
2. making a company, process, or industry more efficient by reorganizing it to reduce or eliminate waste
Usage: British spelling; business context

Examples

• She was rationalising her decision to quit her job by saying it was too stressful.
• He kept rationalising his poor performance instead of working harder.
• The company is rationalising its operations to cut costs.
• They’re rationalising the production process to improve efficiency.
• Stop rationalising your mistakes and take responsibility.
• The government is rationalising public services to save money.