The Collaborative International Dictionary of English v.0.48:

Infield \In*field"\, v. t.
   To inclose, as a field. [R.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Infield \In"field`\, n.
   1. Arable and manured land kept continually under crop; --
      distinguished from outfield. [Scotland] --Jamieson.
      [1913 Webster]

   2. (Baseball) The diamond; -- opposed to outfield. See
      Diamond, n., 5.
      [1913 Webster]

WordNet (r) 3.0 (2006):

infield
    n 1: the area of a baseball field that is enclosed by 3 bases
         and home plate [syn: baseball diamond, diamond,
         infield] [ant: outfield]