blisko

1. closely
   Blisko smo povezani još od školskih dana. — We've had close ties since our school days.
   Dve firme blisko sarađuju već godinama. — The two companies have worked closely together for years.
2. (blisko mi je) familiar; relatable
   Nisam ekspert, ali blisko mi je, pa se snalazim. — I'm not an expert, but it's familiar to me, so I get by.
   Ne bavim se tim poslom, ali mi je blisko, pa razumem o čemu pričaju. — I don't work in that field, but it's familiar to me, so I understand what they're talking about.

For physical distance, blizu is usually used rather than blisko. In predicative use (blisko mi je, to mi je blisko) the form coincides with the neuter of the adjective blizak.