* Bangla: His native language and the language he dedicated his life to researching and promoting.
* Arabic: He studied Islamic literature and theology extensively, requiring fluency in Arabic.
* English: He published numerous academic works in English and taught at various universities in the language.
* Persian: He was well-versed in Persian literature and Islamic history, making proficiency in Persian likely.
* Sanskrit: His research on the origins of Bangla language would have required knowledge of Sanskrit.
Based on his academic profile, it's plausible he had a working knowledge of other languages as well, but those are not definitively confirmed.
It's important to remember that language proficiency is a spectrum, and a scholar like Dr. Shahidullah might have possessed a range of skills from conversational fluency to reading proficiency in different languages.