1) Ballfield of sorts 2) Ballgame site 3) Baseball field of sorts 4) Building site 5) Diamond in the rough 6) Ersatz diamond 7) Field alternative 8) Little League locale 9) Makeshift ballfield 10) Makeshift ballpark 11) Makeshift baseball field 12) Neighborhood ballfield 13) Neighborhood ballpark 14) Place for a ballgame 
• a vacant lot; -- used especially in reference to informal games played by children; as, sandlot baseball.
[n] - a vacant lot used by city boys to play games
noun a vacant lot used by city boys to play games