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:
My job 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.
marathon adjective [onlybeforenoun]:
a marathon journey lasting 56 hours * a marathon legal battle
