/ ˈmærəθən; NAmE -θɑːn/ noun
1.
a long running race of about 42 kilometres or 26 miles :
the London marathon
to run a marathon
2.
an 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.
ORIGIN: 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.
► mara·thon adjective [ only before noun ]:
a marathon journey lasting 56 hours
a marathon legal battle