The word "pigeon-hole" refers to a small compartment or space used for storing or categorizing items. Some synonyms for this word include cubbyhole, slot, compartment, storage unit, and bin. These terms may be used interchangeably depending on the context and the type of items being stored. For instance, "cubbyhole" may be used to refer to a small storage space in a classroom or office, while "bin" is often associated with large containers for storing materials in a warehouse or factory. Overall, there are many words that can be used to describe the act of organizing or categorizing items, and these words can add variety and clarity to writing and communication.