is in Slovenian a base of many words. Basically it means: the second and the other. In a bit more literally Slovenian and everyday Croatian it means “a friend, companion”.
So here is the list of words with the base of *drug
drug – other
drug – second
družina – family
družba – society, company
društvo – association, company
družiti se – to mingle, to be together
drugačen – different
drugoten – of the secondary meaning
zadruga – cooperative
drugače – otherwise, in different way
drugekrati – some other time
drugam – (to go) somewhere else
drugič – second time, some other time
drugje – elsewhere
drugod – other places
predrugačiti – transform
samodrug – to be with someone else
sodrug – companion
…