Strenuous/ˈstrenjuəs/ Definition 1 of 2Pro Tip 1/3Physical Demands Used when describing tasks that require a lot of physical effort and might exhaust you. Climbing the mountain was a strenuous activity. Pro Tip 2/3Intensity Emphasis Highlights the extreme level of effort or energy put into an action or task. Preparing for the performance was a strenuous process. Pro Tip 3/3Mental Exertion Can also refer to tasks that require intense mental effort, not just physical. Solving the advanced puzzles was a strenuous challenge.