The term 'PUT IN A FOOTNOTE' can be summarized by the crossword solution CITE, which is a four-letter word. CITE is a verb meaning to quote or refer to (a book, author, etc.) as an authority for one's statements. It is often used in academic writing to give credit to the original source of information. In this context, it can be used to put in a footnote, which is a note at the bottom of a page that provides additional information about the content on the page.