This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. One that participates in a marathon, especially a marathon runner.

n. Someone who participates in a marathon or other long-distance races.

n. someone who participates in long-distance races (especially in marathons)

"Davila is best known as a marathoner, and if one (i.e., me) had to predict the 2012 U.S."

runner   

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