In response to prompt : Dominant
Bangla (Bengali) is the dominant language in Bangladesh. Majority of the people in Bangladesh, speak Bengali.
Not everyone in this country speak proper Bengali, they speak a dialect which resembles the language.
It’s kind of like in U.K where not all the citizens speak RP( received pronunciation). It is the accent of Standard English in the United Kingdom and is defined in the concise Oxford English Dictionary as the standard of English as spoken in South Of England.
In Bangladesh some of us call it the book language. The received Bengali accent is spoken by a few people. Different provinces have their own dialect, which is not difficult to understand, only the dialect of people from Chittagong, sounds like a different language.
It is like Cockney in U.K which is a problem to understand for visitors.