Infield is a widely used term in sports terminology, its meaning depends on in what sport it is used.
In baseball the baseball diamond plus a rounded region beyond it (see diagram), usually clear of grass, in contrast to the more distant, usually grass-covered outfield. It also refers to the defensive unit of players that are positioned in the region: first baseman, second baseman, shortstop, third baseman and sometimes including the catcher & pitcher who are as a tandem often referred to separately as the battery.
In cricket infield is a central oval on the cricket field (see diagram), the reference point for fielding restrictions in short forms of the game; in contrast to the more distant outfield