- 1a long running race of about 26 miles or 42 kilometers the Chicago marathon to run a marathon
- 2an activity or a piece of work that lasts a long time and requires a lot of effort and patience The interview was a real marathon. From the story that in ancient Greece a messenger ran from Marathon to Athens (22 miles) with the news of a victory over the Persians.
a marathon car trip lasting 56 hours a marathon legal battleSee marathon in the Oxford Advanced Learner's Dictionary
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