n.
    - a person who sees an event take place.
- a person giving sworn testimony to a court of law or the police.
- a person who is present at the signing of a document and signs it themselves to confirm this.
- evidence; proof. ▸open profession of one's religious faith through words or actions. 
v.
   - be a witness to.
- be the place, period, etc. in which (an event or development) takes place.
- be a sign or proof of. ▸
(witness to)
 openly profess one's religious faith in. 
Etymology
  OE witnes (see wit1, -ness).