exertion

Universal Words noun 1 [U] (also exertions [pl.]) physical or mental effort; the act of making an effort: She was hot and breathless from the exertion of cycling uphill. * He needed to relax after the exertions of a busy day at work. 2 [sing.] the use of power to make sth happen: the exertion of force / strength / authority * It requires no great exertion of the imagination to recognize the truth of this.