Definitions of Stress

This blog presents an review of various definitions of stress.

Mental Health

According to the U.S. Department of Health & Human Services (HHS), in 2016, an estimated 43 million American adults—18 percent—met the medical standard for having a mental, behavioral, or emotional disorder that substantially interfered with or limited major life activities.  Of these, 10 million people—or four percent of all American adults—had a serious mental illness.  In 2012, the financial cost of mental disorders was at least $467 billion in the United States.  The 2019 Budget provides $1,065 million for mental health activities.1

What are the causes of Mental Health issues?

WebMD2 says although the exact cause of mental health issues are not known, it is becoming clear through research that many of these conditions are caused by a combination of biological, psychological, and environmental factors. It lists anxiety as the stressor that can trigger the condition.

Mental Health America3 mentions, “Mental health problems may be related to excessive stress due to a particular situation or series of events.”

It is generally accepted that chronic stress and anxiety are main contributing factors that may result into mental health issues.

Definition of Stress

In the field of medical terminologies it is customary to define each word to help understand meaning of that word. Generally, for most of the medical terminologies, there is a universally accepted definition for the term. However, when it comes to the definition of “Stress” it seems like the scientific community has been trying to define stress right from the time this phenomenon was identified, yet there is no universally accepted definition available.

A Google search to “define stress” yields 729 million results. We screened through top pages to see if we can find universally acceptable definition of stress. Here are some of the definitions of stress by State Institutions, Mental Health societies and organizations, Clinics, medical authors, and dictionaries:

Definitions of Stress by State Institutions


Stress is not a useful term for scientists because it is such a highly subjective phenomenon that it defies definition. And if you can’t define stress, how can you possibly measure it? The term “stress”, as it is currently used was coined by Hans Selye in 1936, who defined it as “the non-specific response of the body to any demand for change”.

  • The American Institute of Stress4

According to one of the first researchers to examine stress, stress is “[t]he non-specific response of the body to any demand for change.”

  • Integrative Medicine UCLA5

“Stress is the inability to cope with a perceived or real threat to one’s mental, physical, emotional, and spiritual wellbeing which results in a number of physiological responses and adaptations.”
— Seaward, Brian L. (1994). Managing Stress, Jones and Bartlett, London.

“Stress results from an imbalance between demands and resources.”
— Lazarus, R.S. and Folkman, S. (1984). Stress, Appraisal and Coping, New York: Springer.

“Stress occurs when pressure exceeds your perceived ability to cope.”
— Palmer, S. 1999. 

  • University of Connecticut, Wellness & Prevention Services6

Stress is how the brain and body respond to any demand. Every type of demand or stressor—such as exercise, work, school, major life changes, or traumatic events—can be stressful.

  • National Institute of Mental Health7

Stress is how your body reacts to certain situations, such as sudden danger or long-lasting challenge.

  • Office on Women’s Health at U.S. Department of Health & Human Services8

Definitions of Stress by Mental Health societies and organizations


Stress is hard to define because it means different things to different people

  • Mental Health America9

Stress is primarily a physical response. When stressed, the body thinks it is under attack and switches to ‘fight or flight’ mode, releasing a complex mix of hormones and chemicals such as adrenaline, cortisol and norepinephrine to prepare the body for physical action.

  • Stress Management Society UK10

At the most basic level, stress is our body’s response to pressures from a situation or life event.

  • MentalHealth Foundation UK11

Stress is the body’s reaction to harmful situations — whether they’re real or perceived.


Stress is a state of threatened homeostasis caused by intrinsic or extrinsic adverse forces (stressors)

  • National Center for Biotechnology Information, S. National Library of Medicine in book Endotext under topic Stress, Endocrine Physiology and Pathophysiology13

an organism’s response to a stressor such as an environmental condition

  • Wikipedia17

Definition of Stress by Clinics

Stress is the body’s reaction to any change that requires an adjustment or response. The body reacts to these changes with physical, mental, and emotional responses.

  • Cleveland Clinic14

Definition of Stress by Medical Author

In a medical or biological context stress is a physical, mental, or emotional factor that causes bodily or mental tension. Stresses can be external (from the environment, psychological, or social situations) or internal (illness, or from a medical procedure). Stress can initiate the “fight or flight” response, a complex reaction of neurologic and endocrinologic systems.

  • Medical Author: William C. Shiel Jr.15

Stress is the body’s natural defense against predators and danger. It flushes the body with hormones to prepare systems to evade or confront danger. This is known as the “fight-or-flight” mechanism.

  • Medical News Today16

Definitions of Stress by Dictionaries

great worry caused by a difficult situation, or something that causes this condition:

  • Cambridge Dictionary (as noun)18

A state of mental or emotional strain or tension resulting from adverse or demanding circumstances.

  • English Oxford Dictionaries (as mass noun)

Physiological disturbance or damage caused to an organism by adverse circumstances

  • English Oxford Dictionaries (as Noun- Biology)19

a physical, chemical, or emotional factor that causes bodily or mental tension and may be a factor in disease causation

  • Merriam Webster Dictionary (as noun)20

A specific response by the body to a stimulus, as fear or pain, that disturbs or interferes with the normal physiological equilibrium of an organism.

  • Dictionary (noun – physiology)21

Psychology: (1) As a cause: mental, physical, or social, force or pressure that puts real or perceived demands on the body, emotions, mind, or spirit, and which (when it exceeds the stress-handling capacity of the individual) leqad to a breakdown.

(2) As an effect: physiological effect produced in an organism in its attempts to cope (called adaptive response) with the demands created by a stressor.

  • Business Dictionary22

It is evident that since Hans Selye coined the terms “stress” in 1936, scientific community has not been able to conclusively define the term with a universally acceptable definition of stress. However, general understanding has been that stress is result of some form of stimuli (stressors) that evoke a physiological process manifested by body as the fight or flight response.

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