What term describes an addition or marginal note to a document?

The term that describes an addition or marginal note to a document is "annotation." An annotation refers specifically to a comment, note, or explanation that is added to a text, particularly in the margins or at the end, to provide additional information or context. This practice is common in legal and academic documents to clarify points or make important observations.

In the context of notary practice, it is essential to understand various legal terms and their meanings. While the other options provided may relate to document processing or notes in various contexts—such as an apostille, which certifies the authenticity of documents, or an addendum, which refers to an addition or supplement to a document—these terms do not specifically encapsulate the idea of a marginal note or addition like "annotation" does. Therefore, "annotation" is the most accurate term for a note that is added for clarity or elaboration.