How do you say the Russian word for friend?

Here's how to say it:

* Formal: "Друг" (droog)

* Informal: "Друг" (droog) or "Дружок" (droozhok) for a close friend.

Note: The gender of the noun "друг" is masculine, so you would use the masculine form of adjectives when describing your friend. For example, "хороший друг" (good friend) or "веселый друг" (funny friend).