Late Middle English; earliest use found in Geoffrey Chaucer (c1340–1400), poet and administrator. From Middle French laboureux difficult from labour + -eux. Compare Spanish laboroso.
Definition of laborous in US English:
laborous
(also lawborous, labourous)
adjectiveˈleɪb(ə)rəs
Laborious.
Origin
Late Middle English; earliest use found in Geoffrey Chaucer (c1340–1400), poet and administrator. From Middle French laboureux difficult from labour + -eux. Compare Spanish laboroso.