a written explanation or criticism or illustration that is added to a book or other textual material

make a written note of

a notation written on mail that is to be held at the post office until called for (not in the United States or Canada)

a short note recognizing a source of information or of a quoted passage

a printed note placed below the text on a printed page

a Latin phrase (or its abbreviation) used to indicate that special attention should be paid to something

a note appended to a letter after the signature