Formal:
* Mahāśaya (মহাশয়): This is the most common and respectful way to address a man, similar to "Sir" in English.
* Śrīman (শ্রীমান): This is a more formal and respectful term, usually used for older or highly respected men.
* জনাব (Janab): This is a formal and respectful term borrowed from Urdu and is used for men.
* শ্রীযুক্ত (Sriyukta): This is a very formal term used for addressing someone, especially if they hold a high position or are a respected figure.
* মশাই (Mashai): This is a slightly less formal term than "Mahāśaya", but still respectful. It's often used for older men you know.
Informal:
* ভাই (Bhai): This means "brother" and can be used for male friends or acquaintances, especially if they are younger.
* দাদা (Dada): This means "older brother" and can be used for men slightly older than you, especially if they're close to you.
Important Considerations:
* Age: Respect for age is highly valued in Bengali culture. Always use a respectful term when addressing someone older than you.
* Context: The level of formality depends on the situation. For example, you'd use a more formal term when addressing your teacher or a government official, but a more informal term when talking to a close friend.
* Relationship: The term you use will depend on your relationship with the person.
It's always best to err on the side of formality, especially if you're unsure. A native Bengali speaker will be able to guide you on the most appropriate term to use in a given situation.