krvaviti

1. to make bloody; to stain with blood
   Deca na igralištu stalno krvave kolena. — Kids at the playground are always bloodying their knees.
   Ne želim da krvavim ruke zbog njega. — I don't want to get blood on my hands because of him.
2. (of a wound, nose) to bleed
   Rana mu još krvavi. — His wound is still bleeding.

For "to bleed" the usual verb is krvariti; krvaviti in this meaning is less common.