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Search for: "জীববিজ্ঞান অভিধান pdf" or "Biology dictionary Bengali pdf" . Several pre-2010 dictionaries are out of copyright and available for free. Example: “A Dictionary of Botany and Zoology in Bengali” by Dr. Haripada Mondal (scanned copies exist). biology dictionary bangla pdf
This is widely considered one of the most reliable printed resources, often available as a digital reference. often available as a digital reference.