Definition of labouring oar in English:

labouring oar

(US laboring oar)

noun

  • An oar that works or is worked, especially with difficulty or great effort; (hence figurative) the most difficult or demanding part of an enterprise (now chiefly US). Frequently in "to pull (also tug, ply) the labouring oar" (and variants).

Origin

Early 17th century; earliest use found in Michael Drayton (1536–1631), poet.