By extension, a player who is trying to advance from base to base.(noun)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "baserunner" in a sentence
"Regardless of what actually happens to baserunners (note that our definition of 'baserunner' excludes those rounding the bases on a home run, simply for ease of writing's sake)."
"It handcuffed me because it went through (baserunner Joe) Mauer's leg almost."
"The day before the Bautista trade, he was catching for Triple-A Norfolk when a baserunner collided with him at home plate, tearing the posterior cruciate ligament in Huber's left knee."