pratilac

1. companion; escort
   Deca mogu ući samo uz pratioca. — Children may enter only with an escort.
   Na put je krenuo sa dva pratioca. — He set off on the journey with two companions.
2. (on social media) follower
   Ona ima preko sto hiljada pratilaca na Instagramu. — She has over a hundred thousand followers on Instagram.
3. (of a phenomenon) companion; accompaniment
   Nesanica je čest pratilac stresa. — Insomnia is a frequent companion of stress.

For a woman, the word is pratilja.