One who can give a firsthand account of something seen, heard, or experienced: a witness to the accident. One who furnishes evidence. Something that serves as evidence; a sign. Law One who is called on to testify before a court. Law One who is called on to be present at a transaction in order to attest to what takes place. Law One who signs one's name to a document for the purpose of attesting to its authenticity. An attestation to a fact, statement, or event; testimony. One who publicly affirms religious faith. A member of the Jehovah's Witnesses. To be present at or have personal knowledge of. To take note of; observe. To provide or serve as evidence of. See Synonyms at indicate. To testify to; bear witness. To be the setting or site of: This old auditorium has witnessed many ceremonies. To attest to the legality or authenticity of by signing one's name to. To furnish or serve as evidence; testify. To testify to one's religious beliefs.