difficult to do or needing a lot of effort: (Cambridge)
needing great effort; causing trouble or worry (Oxford)
بیوقوف ,احمق
She found the duties of motherhood onerous. (Cambridge).
The tax bill was aimed at lifting the onerous tax burden from the backs of the middle class.(Oxford)
aimed at lifting the onerous tax burden
an onerous duty/task/responsibility
Difficult
Burdensome
Painful
Easy
Effortless
Onerousness