Breadcrumb Home > Thesaurus > M Synonyms of marathon Find synonyms for: Noun 1. marathon, endurance contest, undertaking, project, task, labor usage: any long and arduous undertaking 2. marathon, footrace, foot race, run usage: a footrace of 26 miles 385 yards 3. Marathon, battle of Marathon usage: a battle in 490 BC in which the Athenians and their allies defeated the Persians WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.Definition and meaning of marathon (Dictionary) TrendingHere are the facts and trivia that people are buzzing about. Chinese New Year History, Meaning, and Celebrations Current Events This Week: February 2024 Valentine's Day Valentine's Day History Mardi Gras 30 "Charlie and the Chocolate Factory" Quotes ✖ Related Content Daily Word Quiz: parallax Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language