foul ball Word Origin noun Baseball.
- a batted ground ball that is hit and played outside the foul lines, or that passes outside the foul lines at first or third base, or that is played outside the foul line between home and first or third base regardless of where hit.
- a batted fly ball played or landing outside the foul lines.
- Slang. an incompetent, unlucky, or eccentric person.
Origin of foul ball An Americanism dating back to 1855–60