/ Thesaurus / H Synonyms of horse thistle Find synonyms for: Noun1. prickly lettuce, horse thistle, Lactuca serriola, Lactuca scariola, compass plant, compass flowerusage: European annual wild lettuce having prickly stems; a troublesome weed in parts of United StatesWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: ontiguous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language