The antonym of 'Onerous' is -

- উল্লেখিত প্রশ্নে Onerous এর antonym হচ্ছে Effortless.
Onerous (adjective)
English Meaning: Difficult to do or needing a lot of effort.
Bangla Meaning: কষ্টসাধ্য; গুরুভার: onerous duties.
Synonyms: Inconvenient (অসুবিধাজনক), Troublesome (বিরক্তিজনক), Hard (কষ্টকর), Cruel (যন্ত্রনাদায়ক), Rough (রুক্ষ্ম)।
Antonyms: Easy (সহজ), Effortless (উদ্যমহীন), Soft (মসৃন), Comforting (আরামদায়ক), Restful (শান্তিপূর্ন)।

Other Forms: Onerously (adverb).
Example Sentence: 
1. The new rules will place onerous responsibilities on employers.
2. The government imposed onerous taxes on imports.

Source: Lecture.