mrs

1. (in orthodox fasting) non-fasting food; meat and dairy food
   Baka za vreme posta ne jede mrs. — Grandma doesn't eat meat or dairy during the fast.
2. non-fast days
   Posle Uskrsa počinje mrs. — After Easter the non-fast period begins.

The related adjective is mrsan (non-fasting), opposite of posni.