/ Thesaurus / L Synonyms of letter box Find synonyms for: Noun1. Post-Office box, PO Box, POB, call box, letter box, compartmentusage: a numbered compartment in a post office where mail is put to be called for2. postbox, mailbox, letter box, maildropusage: public box for deposit of mail3. mailbox, letter box, boxusage: a private box for delivery of mailWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: heifer Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language