1. (a.) Requiring perseverance or sacrifice; toilsome; tiresome\.

2. (a.) Devoted to labor; diligent; industrious; as, a laborious mechanic.

Herculean abstruse ardent arduous assiduous backbreaking brutal burdensome careful complex critical crushing delicate demanding detailed determined difficile difficult diligent dogged effortful energetic exacting exhausting exhaustive fatiguing fervent forced formidable grueling hairy hard hard-earned hard-fought hard-working hardworking heavy hefty indefatigable industrious intricate jawbreaking killing knotted knotty labored mean never idle no picnic not easy obdurate obstinate onerous operose oppressive overworked painful painstaking persevering persistent ponderous punishing relentless rigorous rough rugged scrupulous sedulous set with thorns severe sleepless spiny steadfast steady steep stiff strained strenuous stubborn taxing thorny thorough ticklish tireless tiring toilsome tough tricky troublesome unflagging unrelenting unremitting unsleeping unsparing untiring unwavering unwearied uphill vehement wearisome wearying wicked zealous