(a.) Eagerly pressing or urgent; zealous; ardent; earnest; bold; valiant; intrepid; as, a strenuous advocate for national rights; a strenuous reformer; a strenuous defender of his country.

Herculean active arduous breathless burdensome demanding determined difficult dogged dynamic eager earnest effortful energetic enthusiastic exhausting hard indefatigable intense laborious lusty mean operose persistent pertinacious red-blooded resolute sincere taxing tenacious tireless tiring toilsome tough uphill vigorous vital wicked zealous