1. in a way that relates to the mind or thinking processes
2. using only the mind without writing or speaking aloud

Examples

• She was mentally preparing for the big presentation.
• The math problem was too difficult to solve mentally.
• He seemed mentally exhausted after the long exam.
• I mentally rehearsed my speech before going on stage.
• The athlete was mentally tough despite the pressure.
• She calculated the tip mentally without using a calculator.