n.

1. 努力；费力[U][C]
   She failed to unlock the safe in spite of all her exertions.

   她虽然费尽力气，仍未能将那保险箱的锁打开。

   He was painting the gate with exertion.

   他在费力地油漆大门。

2. （能力、权力等的）运用；行使[U]
   Exertion of authority over others is not always wise.

   以权压人并不总是明智的。