marathon n. 1. A footrace of 26 miles 385 yards. [wns=2][WordNet 1.5]
2. Hence: Any long and arduous undertaking, straining the endurance of the participants. [wns=1]Syn. -- endurance contest.[WordNet 1.5]
3. (Capitalized)a battle in 490 BC in which the Athenians and their allies defeated the Persians. [wns=3]Syn. -- battle of Marathon.[WordNet 1.5]