mar·a·thon 
(mărə-thŏn′)
(mărə-thŏn′)n.
1. Sports
a. A cross-country footrace of 26 miles, 385 yards (42.195 kilometers).
b. A long-distance race other than a footrace: a swimming marathon.
2.
a. A contest of endurance: a dance marathon.
b. An event or activity that requires prolonged effort, endurance, or attention.
[After Marathon (so called because a messenger ran from there to Athens to announce a victory over the Persians in 490 BC).]