A professional witness is someone who is legally authorized to witness and attest to the signing of documents. NOTARY (6 letters) is a term used to describe a person who is authorized to perform certain legal formalities, such as witnessing the signing of documents and administering oaths. NOTARY Public (12 letters) is a more specific term for a NOTARY who has been appointed by a state government and has the authority to perform certain legal acts in that state.