n.

someone who sees an event and reports what happened

同義詞：witnesserinformant

a close observer; someone who looks at something (such as an exhibition of some kind)

同義詞：spectatorviewerwatcherlooker

testimony by word or deed to your religious faith

(law) a person who attests to the genuineness of a document or signature by adding their own signature

同義詞：attestantattestorattestator

(law) a person who testifies under oath in a court of law

Adolescent witnesses to peer suicide.
Adolescent witnesses to a peer suicide
Child witnesses to domestic violence: a meta-analytic review
Optimization of entanglement witnesses
Mitochondrial pseudogenes: evolution's misplaced witnesses.
Efficient Generation of Counterexamples and Witnesses in Symbolic Model Checking
The NIMH community violence project: I. Children as victims of and witnesses to violence.
Psychological and behavioral correlates of family violence in child witnesses and victims
Tell me what happened: Structured investigative interviews of child victims and witnesses.
An experimental study of the effectiveness of different techniques of questioning child witnesses