Wordnet 3.0
NOUN (1)
1. 
 a region in which active military operations are in progress; 
- Example: "the army was in the field awaiting action"- Example: "he served in the Vietnam theater for three years"[syn: field, field of operations, theater, theater of operations, theatre, theatre of operations]
WordNet (r) 3.0 (2006):
field of operations
    n 1: a region in which active military operations are in
         progress; "the army was in the field awaiting action"; "he
         served in the Vietnam theater for three years" [syn:
         field, field of operations, theater, theater of
         operations, theatre, theatre of operations]