Ecophysiology (from Greek οἶκος, oikos, 'house(hold)'; φύσις, physis, 'nature, origin'; and -λογία, -logia), environmental physiology or physiological ecology is a biological discipline that studies the adaptation of an organism's physiology to environmental conditions. It is closely related to comparative physiology and evolutionary physiology. Ernst Haeckel's coinage bionomy is sometimes employed as a synonym. Ecophysiology (from Greek οἶκος, oikos, 'house(hold)'; φύσις, physis, 'nature, origin'; and -λογία, -logia), environmental physiology or physiological ecology is a biological discipline that studies the adaptation of an organism's physiology to environmental conditions. It is closely related to comparative physiology and evolutionary physiology. Ernst Haeckel's coinage bionomy is sometimes employed as a synonym.