Characterized by or performed with much energy or force.

Roget 686: laboring etc. v.. laborious, operose^†, elaborate; strained; toilsome, troublesome, wearisome; uphill; herculean, gymnastic, palestric^†.    hard-working, painstaking; strenuous, energetic.    hard at work, on the stretch.    ... show more

Roget 604a: persevering, constant; steady, steadfast; undeviating, unwavering, unfaltering, unswerving, unflinching, unsleeping^†, unflagging, undrooping^†; steady as time; unrelenting, unintermitting^†, unremitting; plodding; industrious etc. 682; strenuous etc. 686; pertinacious; persisting, persistent.    solid, sturdy, staunch, stanch, true to oneself; unchangeable etc. 150; unconquerable etc. (strong) 159; indomitable, game to the last, indefatigable, untiring, unwearied, never tiring.    ... show more

Roget 682: active, brisk, brisk as a lark, brisk as a bee; lively, animated, vivacious; alive, alive and kicking; frisky, spirited, stirring.    nimble, nimble as a squirrel; agile; light-footed, nimble-footed; featly^†, tripping.    quick, prompt, yare^†, instant, ready, alert, spry, sharp, smart; fast etc. (swift) 274; quick as a lamplighter, expeditious; awake, broad awake; go-ahead, live wide-awake [U.S.] etc. (intelligent) 498.    forward, eager, strenuous, zealous, enterprising, in earnest; resolute etc. 604.    industrious, assiduous, diligent, sedulous, notable, painstaking; intent etc. (attention) 457; indefatigable etc. (persevering) 604.1; unwearied; unsleeping^†, never tired; plodding, hard-working etc. 686; businesslike, workaday.    bustling; restless, restless as a hyena; fussy, fidgety, pottering; busy, busy as hen with one chicken.    working, at work, on duty, in harness; up in arms; on one's legs, at call; up and doing, up and stirring.    busy, occupied; hard at work, hard at it; up to one's ears in, full of business, busy as a bee, busy as a one-armed paperhanger.    meddling etc. v.; meddlesome, pushing, officious, overofficious^†, intrigant^†.    astir, stirring; agoing^†, afoot; on foot; in full swing; eventful; on the alert, etc. (vigilant) 459.    ... show more

Taxing to the utmost; testing powers of endurance:
— A strenuous task.

synonyms: arduous, straining.