hellacious, killer, operose, exacting, weighty, sound, pick-and-shovel, straining, lowering, clayey, large, fleshy, grueling, dense, laboured, Augean, persnickety, rigorous, backbreaking, moiling, leaden, surd, big, great, voiceless, knockout, intemperate, labourious, strong, grave, gruelling, expectant, overweight, herculean, wakeless, tall, unvoiced, concentrated, enceinte, exhausting, effortful, stiff, sullen, ponderous, testing, cloggy, threatening, weighed down, punishing, sonorous, killing, impenetrable, profound, murderous, heavy, challenging, taxing, grievous, sweaty, lumbering, labored, with child, gravid
difficult (part of speech: adjective)
formidable, stressful, cumbersome, contrary, severe, arduous, knotty, demanding, harsh, oppressive, uphill, thorny, tricky, finicky, hard, fussy, troublesome, difficult, wearing, tough, strenuous, wearying, complicated, complex, cantankerous, ticklish, rugged, burdensome, wearisome, grinding, adverse, tight, laborious, rough, onerous, trying, bothersome
weary (part of speech: adjective)
depressed, worn-out, apathetic, cheerless, wayworn, feeble, frazzled, drowsy, sleepy, faint, tired, debilitated, flaccid, droopy, blue, limp, footsore, over-weary, run-down, wasted, listless, exhausted, weak, bored, fatigued, weary
dull (part of speech: adjective)
- A toilsome march over these " Alps rising over Alps!" - "Curiosities of Literature, Vol. 3 (of 3)", Isaac Disraeli.
- Sometimes, however, the foragers returned well laden with good things, and as good comrades should, shared the fruits of their toilsome hunt with their comrades. - "Detailed Minutiae of Soldier life in the Army of Northern Virginia, 1861-1865", Carlton McCarthy.
- They made an effort to prosecute their journey along the banks, but, after some toilsome days, strength and spirits failed, and they gave up in despair! - "History-of-the-Conquest-of-Peru-with-a-preliminary-view-of-the-civilization-of-the-Incas", Prescott, William Hickling.