Formal:
* நண்பர் (nanbar) - This is the most common and formal way to say "friend" for both male and female friends.
Informal:
* நண்பன் (nanban) - This is the informal term for a male friend.
* நண்பி (nanpi) - This is the informal term for a female friend.
* நண்பர்கள் (nanbarkal) - This is the plural form of "friend" and can be used for both male and female friends.
* சகோதரர் (sakodharar) - This literally means "brother" but can also be used to refer to a close friend.
Other options:
* நெருங்கிய நண்பர் (nerungiya nanbar) - This means "close friend".
* சிறந்த நண்பர் (sirantha nanbar) - This means "best friend".
You can choose the appropriate term based on the situation and your relationship with the person.