1 to see something happen, especially an accident or crime -- assistere a, essere presente a
Did anyone witness the attack? C’è qualcuno che era presente all’aggressione?
2 a person who has seen or was present at an event etc and so has direct knowledge of it -- testimone
3 a person who gives evidence, especially in a law court -- testimone
a witness for the prosecution.
4 a person who adds his signature to a document to show that he considers another signature on the document to be genuine -- testimone