1a person who sees an event, typically a crime or accident, take place:police are appealing for witnesses to the accidentI was witness to one of the most amazing comebacks in sprinting history
a person giving sworn testimony to a court of law or the police:a key witness at the trial [as modifier]:oral evidence set down in witness statements
a person who is present at the signing of a document and signs it themselves to confirm this:a deed signed in the presence of a witness
2 [mass noun] evidence; proof:the memorial service was witness to the wide circle of his interests
used to refer to confirmation or evidence given by signature or under oath:in witness thereof, the parties sign this document
open profession of one’s religious faith through words or actions:they will be able to give witness of their faith and confidence in God
3 (also witness mark) a line or remnant of an original surface on a workpiece to show how much material has been removed or the shape of the original outline.
1see (an event, typically a crime or accident) happen:staff who witnessed the murder
be present as someone signs (a document) or gives (their signature) to a document and sign it oneself to confirm this:the clerk witnessed her signature
2have knowledge of (a development) from observation or experience:what we are witnessing is the birth of a dangerously liberal orthodoxy
be the place, period, or setting in which (an event or development) takes place:the 1980s witnessed an unprecedented increase in the scope of the electronic media
be a sign or proof of (something); serve as evidence:the mid-1980s saw an intensification of interest in community care, as witnessed by the publication of four major reports [no object]:his writings witness to an inner toughness
[in imperative] used to introduce an example that proves a preceding statement:the nuclear family is a vulnerable institution—witness the rates of marital breakdown
3 [no object] openly profess one’s religious faith:one of the purposes of his coming was to nerve the disciples to witness to Jesus
as God is my witness (or God be my witness)
an invocation of God as confirmation of the truth of a statement:God be my witness, sir, I didn’t!
call someone/thing to witness
archaic appeal or refer to someone or something for confirmation or evidence of something.