Add a superscript number after the word you want to define. A superscript is a character that is smaller than the rest of the text and is aligned slightly above the words around it. The number refers to how many footnotes are on the page. If this is the first footnote, you would use "1," but if it is the third, you would use "3." In most word processing programs, you can insert a footnote from the menu options; the program will keep track of the numbers for you.
Place a footnote at the bottom of the page where it is referenced. Write the number associated with the footnote as a superscript, followed by the word you are defining and its definition. Be brief and shorten definitions that are longer than a couple of sentences.
Add an in-text citation to the end of the footnote to show where the information comes from. In parenthesis, write the title of the dictionary where you found the definition, followed by a comma, and the year it was published or the edition number. Make sure to place quotes around the definition if you are directly quoting it from the source and italicize the dictionary's title.
Make sure to include the dictionary in your list of "References" at the end of the document.