Breadcrumb Home > Thesaurus > W Synonyms of windowsill Find synonyms for: Noun 1. windowsill, sill usage: the sill of a window; the horizontal member at the bottom of the window frame WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.Definition and meaning of windowsill (Dictionary) TrendingHere are the facts and trivia that people are buzzing about. Hanukkah Origins of the Christmas Holiday Jewish Holidays, 2010-2030 (A.M. 5770-5791) Western Christian Holidays, 2010-2030 Krampus: The Christmas Devil Kwanzaa ✖ Related Content Daily Word Quiz: tintinnabulation Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language