1. in a way that is not fair, sensible, or appropriate
2. to an extent that is more than what is normal or acceptable

Examples

• The landlord was acting unreasonably by refusing to fix the broken heater.
• She became unreasonably angry over a minor mistake.
• The test was unreasonably difficult for students at that level.
• He was unreasonably demanding about every small detail.
• The price increase seemed unreasonably high.
• The boss was being unreasonably critical of her work.
• It’s unreasonably cold for this time of year.