Guide word and Running head

Guide word noun - A word printed at the top of the page of a dictionary or other reference book to indicate the first or last item on that page.

Running head and guide word are semantically related. In some cases you can use "Running head" instead a noun phrase "Guide word".

Running head noun - A heading printed at the top of every page (or every other page) of a book.

Guide word and running head are semantically related. You can use "Guide word" instead a noun phrase "Running head".