najboljim
Najboljim is a word in several South Slavic languages, including Croatian, Serbian, and Bosnian. It is the instrumental plural form of the adjective "najbolji," which translates to "best" in English. As an instrumental case, "najboljim" is used to indicate the means by which something is done, or to express accompaniment or a certain characteristic.
For instance, one might say they are happy "najboljim" friends, meaning with their best friends. Or, a