Wiktionary
base runner
n. (context baseball English) (alternative spelling of baserunner English)
WordNet
base runner
n. a baseball player on the team at bat who is on base (or attempting to reach a base) [syn: runner]
Usage examples of "base runner".
In every case the base runner should be run down as quickly as possible, and always toward the base farthest from the home plate, so that if an error is made the runner will gain no advantage.
And here, again, the best base runners are oftenest caught because they take the most ground.
Then, if fumbled, he may still have time to get it back to the infield before base runners can take an extra base.