noun

1. an attesting of a fact, statement, etc.; evidence; testimony
2. a person who saw, or can give a firsthand account of, something
3. a person who testifies in court
4. a person called upon to observe a transaction, signing, etc. in order to testify concerning it if it is later held in question
5. something providing or serving as evidence

Etymology: ME witnesse < OE (ge)witnes, witness, knowledge, testimony < witan, to know: see wise & -ness

transitive verb

1. to testify to
2. to serve as evidence of
3. to act as witness of, often, in proof thereof, signing a statement that one has done so
4. to be present at; see personally
5. to be the scene or setting of a hall that has witnessed many conventions

intransitive verb

1. to give, or serve as, evidence; testify
2. to testify to religious beliefs or faith