airfield; area; arena; athletic field; bailiwick; battlefield; battleground; champaign; discipline; domain; field of battle; field of force; field of honor; field of operation; field of operations; field of study; field of view; flying field; force field; landing field; line of business; orbit; plain; playing area; playing field; sphere; study; subject; subject area; subject field; theater; theater of operations; theatre; theatre of operations;