Which one is the synonym of the word 'Supposition'?

Supposition (noun)
English Meaning: An idea that something may be true, although it is not certain.
Bangla Meaning:
(১) [uncountable noun] অনুমান; কল্পনা: Your theory is based on mere supposition.
(২) [countable noun] অনুমান; আন্দাজ; আঁচ: His suppositions were proved false.
on this supposition; on the supposition that ...যদি ধরে নেওয়া যায় যে…।

Synonyms: Suspicion (সন্দেহ; সংশয়; অবিশ্বাস), Belief (বিশ্বাস; আস্থা), Assumption (অনুমান).
Antonyms: Fact ((প্রকৃত) ঘটনা), Certainty (নিশ্চয়তা), Assurance (আত্মপ্রত্যয়; আত্মবিশ্বাস).

Source: Lecture