playing field

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A field for games such as football and soccer, especially when marked according to specified dimensions according to the game's rules.
• noun The conditions or circumstances in which competition takes place.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A field on which a game, esp. a ball game, is played.
• noun figuratively Any place or context within which competitive activity takes place, such as market competition between companies.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the circumstances under which competition occurs
• noun a piece of land prepared for playing a game