1) Annotate 2) Cite 1) Annotation 2) Asterisk material 3) Bit of extra reading 4) Certain explanation 5) Explanation 6) Fact addition 7) Footer 8) Gloss 9) Marginal note 10) Notation 11) Note 12) Print below the text 13) Reference citation 14) Sound from a shoehorn 15) Terminal comment 16) To add footnotes to a text 17) What an asterisk may indicate 
• (n.) A note of reference or comment at the foot of a page.
A note to provide references, explanations, or comments. The user can usually place footnotes at the bottom of a page or at the end of a document by using the Footnote command on the Insert menu. To view and edit footnotes, choose Footnotes from the View menu. See Comments.
Foot'note` noun A note of reference or comment at the foot of a page. 
[n] - a printed note placed below the text on a printed page
An explanation of a point, placed at the bottom of a page.
additional information which is printed at the bottom of the page rather than in the main body of the text.
footer noun a printed note placed below the text on a printed page
Note at the bottom of the page of a book, indicated by a small letter or a number attached to a word used to prevent a sentence or explanation becoming over-complex