1.
witness
A person who saw or heard something relevant, especially in a legal context, or someone who attests to the truth of a document or event.
証人 refers to a person who testifies or attests to something, primarily in legal and official contexts.
Common collocations
Usage
In legal proceedings, 証人 refers to a person who testifies, while 証拠 refers to physical evidence. Outside courts, 証人 also appears in everyday contexts like marriage registrations, which require two witnesses.