Definition - What does Hostile Witness mean?
A hostile witness is a witness who is openly antagonistic to the attorney who is questioning them. Hostile witnesses often show opposition to the party that called them to the stand, and show that they want that party to lose the lawsuit.
If a judge declares that the witness is hostile, then they will allow the attorney to ask the witness leading questions, even if it was the attorney who called the witness to the stand.
Justipedia explains Hostile Witness
Hostile witnesses can be a problem in trials. The reason is because they often express a clear bias against the party who is questioning them. People who express such biases may be more inclined to try to answer questions in a way that sabotages the argument that the particular party is trying to make. In other words, they are a threat to the integrity of the trial process. This is why judges often allow hostile witnesses to be asked leading questions—in order to try to make the questioning more balanced.