Foul ball lines

(Baseball) lines from the home base, through the first and third bases, to the boundary of the field.

See also: Foul

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in periodicals archive ?
Under the new rule the first and third basemen will not be required to stand as near to the foul ball lines as hitherto.