Noun
marginal note (plural marginal notes)
A note in the margin of a document.
Synonym: marginalia
Coordinate terms: footnote, headnote, endnote
Although a marginal note in the letter suggests that Duchamp generally approved of the statement, Richter did not make the distinction clear until many years later. Source: Internet
The preface probably dates from the late ninth century; the marginal note is on the F manuscript of the Chronicle, which is a Kentish version dating from about 1100. Source: Internet