witness/ 'wɪtnɪs /

1.noun [c] 
(gen,also in court) 目击者

2.noun
(to document) 联署人

3.vt.[+event] 
(see) 目击

4.vt.[fig] 
(experience) 经历

5.vt.[+signature] 
(confirm) 联署

witness for the prosecution
控方证人
witness for the defence
辩方证人
to be (a) witness to sth
为某事的目击者
to bear witness to sth
表明某事
to witness to sth
为某事作证