ex ‧ er ‧ tion /ɪɡˈzɜːʃ ə n $ -ɜːr-/ BrE AmE noun [uncountable and countable]
1 . a lot of physical or mental effort:
The afternoon’s exertions had left us feeling exhausted.
mental exertion
2 . the use of power, influence etc to make something happen:
the exertion of authority