a witness who has knowledge not normally possessed by the average person concerning the topic that he is to testify about
perceive or be contemporaneous with
a close observer; someone who looks at something (such as an exhibition of some kind)
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
(law) a person who testifies under oath in a court of law
a person with special knowledge or ability who performs skillfully
