• Conundrum (noun)

English Meaning: A problem that is difficult to deal with.
Bangla Meaning: কঠিন প্রশ্ন; বাধা।

Synonyms:
Problem (সমস্যা; জটিলপ্রশ্ন),
Mystery (অস্পষ্টতা; রহস্যময়তা),
Quandary (দ্বিধা; কিংকর্তব্যবিমূঢ়তা),
Trouble (ঝামেলাপূর্ণ),
Enigma (ধাঁধা/প্রহেলিকা)।

Antonyms:
Obviousness (সুস্পষ্টতা),
Sure thing (সঠিক, নিশ্চিত বিষয়),
Certainty (নিশ্চিন্ততা),
Solution (সমাধান),
Simplicity (সরলতা)।

Example Sentence:
1. Arranging childcare over the school holidays can be a real conundrum for working parents.
2. The problem remains a conundrum to me, and I hope others can propose ways of dealing with it.

Other options:

Banal (adjective)
English Meaning: Too often used in the past and therefore not interesting.
Bangla Meaning: মামুলি; গতানুগতিক; তুচ্ছ।

Tortuous (adjective)
English Meaning: Full of twists and turns; not straight or direct.
Bangla Meaning: আঁকাবাঁকা, জটিল, প্যাঁচানো।

Phlegmatic (adjective)
English Meaning: Not easily excited or emotional; calm.
Bangla Meaning: স্বভাবত উদাসীন।

Source: Live MCQ Lecture.