Definition 1:
A technical term for a document.
More information
The term instrument is used in the boiler plate wording for notary certificates in many states. A notary can perform an acknowledgment if the signers name is subscribed to the within instrument and they acknowledge that they executed the same in their authorized capacity(ies). This means that the signers name is mentioned in the document and that the signer signs the document at some point before they have their signature notarized. The signer could sign the document a year before they see the notary, or in the notary's presence. Then, the signer must acknowledge that they signed the document and have the signature notarized.