marathon (marathons plural )
1 n-count A marathon is a race in which people run a distance of 26 miles, which is about 42 km.
...running in his first marathon..., Rodgers can also claim four victories in the New York Marathon.
2 adj If you use marathon to describe an event or task, you are emphasizing that it takes a long time and is very tiring.
ADJ n (emphasis)
People make marathon journeys to buy glass here., ...a marathon session of talks with government representatives.