Year	Author	Definition
1974	Freudenberger	Feeling of failure and exhausted or worn existence, as a result of the overload due to the demands of energies, personal resources or spiritual strength of the worker.
1978	Pines and Kafry	It is characterized by feelings of depression, emotional and physical emptying with a negative attitude towards life, the environment and towards itself, the product of a traumatic, sudden and abrupt life event, or as a result of a slow and gradual daily process.
1980	Edelwich and Brodsky	Progressive loss of idealism, energy and motives lived by people as a result of working conditions.
1990	Starrin, Larsson and Styborn	Stress can be experienced positively or negatively by the individual, burnout is an exclusively negative phenomenon. They relate in the sense that burnout could be similar to a negative stress.
1999	Gil-Monte and Peiro	Process involving cognitive-aptitudinal components (low personal fulfillment at work), emotional (emotional exhaustion) and attitudinal (depersonalization).
2002	Oplatka	It is a phenomenon related to professional experience. Its components are interconnected with variables such as commitment and job satisfaction, attitude towards staff and management oriented towards innovation.
2004	Vinaccia and Alvaran	The response to chronic stress is composed of negative attitudes and feelings towards the people with whom they work and their own professional role; As well as being emotionally exhausted.
2005 2010	Gil-Monte; Gil-Monte and Zuñiga.	It is characterized by a cognitive deterioration, consisting in the loss of the illusion by the work or the low personal realization in it; By an affective deterioration characterized by emotional and physical exhaustion; And by the appearance of negative attitudes and behaviors towards clients and towards the organization in the form of indifferent, cold, distant and even harmful behaviors. Occasionally, these symptoms are accompanied by feelings of guilt.