/ Thesaurus / P Synonyms of paper knife Find synonyms for: Noun1. letter opener, paper knife, paperknife, knifeusage: dull knife used to cut open the envelopes in which letters are mailed or to slit uncut pages of booksWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: cygnet Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language