onerous

/ˈɒnəɹəs/adjective

Requiring so much effort that it feels like a heavy load; hard to bear.

Example sentence

“Filling out all the paperwork by hand was an onerous task.”

Formal. From Latin onus, a burden, a word English also uses directly: the onus is on you to prove it.

Related words

onionA round vegetable of the garlic family, made of strong-smelling layers, eaten cooked or raw and used to flavour food.ominousSuggesting that something bad is about to happen; acting as a warning sign.opaqueA dark area or region where no light passes through.omeletA dish of beaten eggs fried flat in a pan, often folded around a filling (the US spelling of omelette).opponentA person who competes against you or takes the opposite side, and tries to stop you from succeeding.ointmentA thick, oily cream, usually containing medicine, that you rub on the skin to treat or soothe it.