Nouns

(n)witness, witnesser, informantsomeone who sees an event and reports what happened
(n)spectator, witness, viewer, watcher, lookera close observer; someone who looks at something (such as an exhibition of some kind)“the spectators applauded the performance”, “television viewers”, “sky watchers discovered a new star”
(n)witnesstestimony by word or deed to your religious faith
(n)witness, attestant, attestor, attestator(law) a person who attests to the genuineness of a document or signature by adding their own signature
(n)witness(law) a person who testifies under oath in a court of law

Verbs

(v)witnessbe a witness to“She witnessed the accident and had to testify in court”
(v)witness, find, seeperceive or be contemporaneous with“We found Republicans winning the offices”, “You'll see a lot of cheating in this school”, “The 1960's saw the rebellion of the younger generation against established traditions”, “I want to see results”