Open English Wordnet
Nouns
(n)battlefield, battleground, field of battle, field of honor, fielda region where a battle is being (or has been) fought“they made a tour of Civil War battlefields”
(n)discipline, subject, subject area, subject field, field, field of study, study, bailiwicka branch of knowledge“in what discipline is his doctorate?”, “teachers should be well trained in their subject”, “anthropology is the study of human beings”
(n)field, field of force, force fieldthe space around a radiating body within which its electromagnetic oscillations can exert force on another similar body not in contact with it
(n)field, field of operation, line of businessa particular kind of commercial enterprise“they are outstanding in their field”
(n)playing field, athletic field, playing area, fielda piece of land prepared for playing a game“the home crowd cheered when Princeton took the field”
(n)field, field of operations, theater, theater of operations, theatre, theatre of operationsa 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”