/kiː ˈwɪtnəs/ – Phrase
Definition: nhân chứng chủ chốt.
A more throughout explanation: A “key witness” is a person who plays a crucial role in a legal case by providing important testimony or evidence that is essential to the case’s outcome. This individual’s testimony is often central to proving or disproving key elements of the case.
Example: The key witness provided crucial testimony that helped secure the conviction of the defendant.