Webster's Revised Unabridged Dictionary · 1913

Laborious

Laborious , adjective

[Latin laboriosus, from labor labor: compare French laborieux.]

1.
Requiring labor, perseverance, or sacrifices; toilsome; tiresome.
Dost thou love watchings, abstinence, or toil, Laborious virtues all? Learn these from Cato. — Addison
2.
Devoted to labor; diligent; industrious; as, a laborious mechanic.