reflex

American  

[ree-fleks, ri-fleks] / ˈri flɛks, rɪˈflɛks /

adjective

1. Physiology. noting or pertaining to an involuntary response to a stimulus, the nerve impulse from a receptor being transmitted inward to a nerve center that in turn transmits it outward to an effector.

2. occurring in reaction; responsive.

3. cast back; reflected, as light, color, etc.

4. bent or turned back.

5. designating a radio apparatus in which the same circuit or part performs two functions.

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noun

1. Physiology.

   1. Also called reflex act.  movement caused by a reflex response.

   2. Also called reflex action.  the entire physiological process activating such movement.

2. any automatic, unthinking, often habitual behavior or response.

3. the reflection or image of an object, as exhibited by a mirror or the like.

4. a reproduction, as if in a mirror.

5. a copy; adaptation.

6. reflected light, color, etc.

7. Historical Linguistics. an element in a language, as a sound, that has developed from a corresponding element in an earlier form of the language.

   The (ō) in “stone” is a reflex of Old English ā.

8. a reflex radio receiver.

9. a reflex camera.

verb (used with object)

1. to subject to a reflex process.

2. to bend, turn, or fold back.

3. to arrange in a reflex system.

reflex British  

noun

1. 1. an immediate involuntary response, esp one that is innate, such as coughing or removal of the hand from a hot surface, evoked by a given stimulus

   2. ( as modifier ) See also reflex arc

      a reflex action

2. 1. a mechanical response to a particular situation, involving no conscious decision

   2. ( as modifier )

      a reflex response

3. a reflection; an image produced by or as if by reflection

4. a speech element derived from a corresponding form in an earlier state of the language

   "sorrow" is a reflex of Middle English "sorwe"

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adjective

1. maths (of an angle) between 180° and 360°

2. (prenominal) turned, reflected, or bent backwards

verb

1. (tr) to bend, turn, or reflect backwards

reflex Scientific  

/ rē′flĕks′ /

1. An involuntary physiological response to a stimulus, as the withdrawal of a body part from burning heat.

2. An unlearned or instinctive response to a stimulus.

3. Also called unconditioned response

4. See more at classical conditioning

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reflex Cultural  

1. An action or movement not controlled by conscious thought. A reflex may be anything from a hiccup to the involuntary response of a body part, such as the action that occurs in the knee-jerk reflex.

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Other Word Forms

• multireflex
  noun
• reflexibility
  noun
• reflexible
  adjective
• reflexly
  adverb
• reflexness
  noun
• semireflex
  noun

Etymology

Origin of reflex

1500–10; < Latin reflexus bent back, past participle of reflectere to reflect

Explanation

A reflex is an action your body does without your thinking about it, like sneezing, or jumping a little when you dream you’re falling. If you suddenly catch a ball before it crashes into a window, you have quick reflexes. When a doctor hits your knee with a little hammer during a physical, it makes your leg kick, even though you didn't consciously make your leg move. The doctor is testing your reflexes — movements that happen without your control. If your reflexes aren't working, it could mean there's something wrong with your body. Putting your hands out when you fall is a reflex. So is laughing so hard you snort.

Example Sentences

Months after I stopped breastfeeding my last child, though, a random Google search led me to discover a term I had never heard of before: D-MER, short for Dysphoric Milk Ejection Reflex.

From Slate • Mar. 15, 2026

Paul Mustone, the president of the Reflex Lighting Group, which now owns the company that originally installed the system in 2012, said they are ready to go next month.

From Seattle Times • Jan. 23, 2023

In some cases, such as with the Reflex app, the data is processed directly on the phone — rather than in the cloud, Brightlamp CEO Kurtis Sluss said.

From Salon • Jan. 17, 2023

By the way, the Reflex comes with three already configured paddle profiles, the FPS for the shooters, and ones more aligned with sports and racing games.

From Washington Times • Nov. 26, 2022

Reflex actions are of several kinds; of these the simplest type, and the one most easily studied, is the muscular contraction due to the excitation of the sensory nerve endings located in the skin.

From The Psychology of Singing A Rational Method of Voice Culture Based on a Scientific Analysis of All Systems, Ancient and Modern by Taylor, David C. (David Clark)