Breadcrumb Home > Thesaurus > P Synonyms of plumb rule Find synonyms for: Noun1. plumb rule, plumb line, perpendicularusage: a plumb line attached to a narrow boardWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. ✖ Related Content Daily Word Quiz: sepulture Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language