/ Thesaurus / R Synonyms of romaine lettuce Find synonyms for: Noun1. cos lettuce, romaine lettuce, Lactuca sativa longifolia, lettuceusage: lettuce with long dark-green spoon-shaped leaves2. cos, cos lettuce, romaine, romaine lettuce, lettuceusage: lettuce with long dark-green leaves in a loosely packed elongated headWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: abominable Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language