1. A reference to an unusually long period of time or a difficult task: There was a marathon session of Congress for several days before the new tax bill was passed.

There were marathon sessions of negotiating with union leaders and company administrators which were not resolved for over a month.

Yesterday, Professor Martin had a marathon time marking 75 examination papers for his literature class.

2. Relating to a great distance or duration: The mountain climbers went on a marathon journey up in the alpines that lasted for three weeks.

Jan's company has been having marathon days of work in order to fill all of the orders that have been coming in for the products.