A dictionary is a resource that lists the words in a language each with its definition and in some cases information about pronunciation, origin or examples on how to use the word. Dictionaries list words alphabetically which means words are not randomly organized but follow a strict organization system and include guide words that facilitate the process of finding a word. The term guide words refer to the words (usually two words) printed in the top of pages of dictionaries that show the first and last word entry that the reader can find in a specific page.
This means guide words tells the reader the words that he or she can find in each page which makes the process of looking for a specific word easier and faster. Considering this if you are looking for the word "buoy" in a diction the two guide words that you could find at the top of the page are "Bun-Buppie" as these words show the page includes words that in terms of alphabetical organization are between "Bun" and "Buppie" including the words bundle, bungalow, and buoy which is the word you are looking for.
