A party that the court feels is hostile against the party they are supposed to testify for. They can be cross examined if they are called. They can be impeached by their own credibility.
Polarize is to force a something or someone to go in only one direction, or to cause people to divide into two very distinct groups. 1  When a special microscope forces the transverse waves created by a light to be focused only in one direction, this is an example of when it polarizes. When a political leader pits one group of people in society against another using inflammatory speech, this is an example of when he polarizes the groups.
The definition of polarized is something that causes light to vibrate in a pattern or that causes something to have opposite (positive and negative) charges. An example of something polarized are the lenses in sunglasses. An example of something polarized is an electrical circuit.