Onerous – Relating to a task which is difficult to do or requires a great deal of effort
The owner made us (onerous) work all day. It required a great deal of effort to keep up.
Examples of onerous in a sentence
Taking care of the puppy is an onerous task.
The flight attendant was not prepared to deal with the onerous passenger.
Even though the computer will speed up our research efforts, the project will still be onerous.