Definition of reflex in US English:



  • 1An action that is performed as a response to a stimulus and without conscious thought.

    ‘a newborn baby is equipped with basic reflexes’
    • ‘Sleep on your back - when the spit collects back there, it triggers a swallowing reflex.’
    • ‘Border Collies have a high startle reflex, which can sometimes endanger their lives.’
    • ‘It must be remembered that some individuals do not have a blink reflex, due to neuro-muscular problems with the eye, and therefore are at serious risk from this laser exposure.’
    • ‘Neurologic examination revealed symmetric reflexes with normal sensation and strength.’
    • ‘Two significant complications of lung transplantation include the impairment of the cough reflex and mucociliary clearance.’
    • ‘The medulla controls this involuntary swallowing reflex, although voluntary swallowing may be initiated by the cerebral cortex.’
    • ‘He saw people as conditioned reflexes, not souls with intentions, willpower and choice.’
    • ‘All his paradigm required was linking and relinking stimuli and responses: a salivary reflex, once produced by food, was now evoked by a bell signaling the coming of food.’
    • ‘Elevation of the larynx during the swallowing reflex protects the airway and opens the upper esophageal sphincter.’
    • ‘Pavlov's studies investigated the way in which environmental stimuli inspired biological reflexes in animals.’
    • ‘Deep tendon reflexes disappear within the first few days of symptom onset.’
    • ‘Secretion into the bloodstream is increased by the presence of food, particularly protein, in the stomach, and is also stimulated by neural reflexes.’
    • ‘Monitor urine output, deep tendon reflexes and serum levels.’
    • ‘These are inhibitory reflexes, excited by deglutition, by gastric distension, and by intestinal dilatation.’
    • ‘Either mechanical tapping or electrical stimulation of the supraorbital regions may evoke the blink reflex.’
    • ‘These receptors also excite the defecation reflex.’
    • ‘My patient still had a few elicitable neurological reflexes.’
    • ‘Thinking about your baby can stimulate the let-down reflex.’
    • ‘They act on the brain to hold back the cough reflex.’
    • ‘Families frequently misdiagnose their loved ones' involuntary muscle reflexes as consciousness.’
    1. 1.1reflexes A person's ability to respond quickly.
      ‘he was saved by his superb reflexes’
      • ‘With lightning quick reflexes, Amanda pushed the button on her bracelet and raised an invisible shield around herself.’
      • ‘He says it slows reflexes and impairs concentration.’
      • ‘Naturally, he honed his reflexes in college - in a midday problems and statistics class.’
      • ‘Other goaltenders have faster glove hands, quicker feet, and swifter reflexes.’
      • ‘Medical students found the tendon strike more difficult to perform and to interpret in people with brisk reflexes than the plantar strike, but this wasn't true for the experienced doctors.’
      • ‘Ben was gifted with an athletic body, an alert mind and quicksilver reflexes, as Neville Abeygoonawardene was later to write.’
      • ‘To control the sled takes all his concentration, muscle control and cat-like reflexes.’
      • ‘Only good reflexes, quick feet and a great deal of luck saved Karae from a severe blow from the back of her father's hand.’
      • ‘He has catlike reflexes, he is skilled with a gun, and his detective work is top-notch.’
      • ‘Your doctor may test your reflexes and muscle strength, and check the pattern of muscle weakness.’
      • ‘Only fast reflexes saved the party's lives.’
      • ‘Then with lightning quick reflexes she pinned Rachel to the grass.’
      • ‘Excellent reflexes are essential for efficient and dignified fly-combat.’
      • ‘The man had lightning-fast reflexes, and he'd already proven himself more than apt at killing in hand-to-hand confrontations.’
      • ‘For starters, you're going to need reflexes, and you have to think quickly on your feet.’
      • ‘A former shortstop, Chavez has quick feet, good range, great reflexes and a strong arm, and he has generally avoided errors of inexperience.’
      • ‘A flash of movement and my lightning quick reflexes were all that saved me.’
      • ‘Only Cameron's lightning fast reflexes saved him from being stabbed in the gut.’
      • ‘I was almost too caught up in my thoughts to block a strike to my left side, but I had fast reflexes and shifted my feet so that I just dodged him.’
      • ‘He's also got a wit as sharp as his reflexes; following Lewis' annihilation of Michael Grant last April, Byrd publicly asked Lewis if he could be next.’
    2. 1.2 (in reflexology) a response in a part of the body to stimulation of a corresponding point on the feet, hands, or head.
      as modifier ‘reflex points’
      • ‘When the nervous system becomes involved, the muscle tendon bundles remain hypertonic and pain reflexes in the area are activated.’
      • ‘The reflexes in the feet are stimulated with various massage techniques to promote healing in the body.’
      • ‘Applying pressure to reflex points makes it possible to interact with the interconnected systems of the body at an energetic level and restore homeostatic function.’
      • ‘The points on the ear have their reflex to different bodily functions or organs.’
  • 2A thing which is determined by and reproduces the essential features or qualities of something else.

    ‘politics was no more than a reflex of economics’
    • ‘In doing so they constitute a public and communal reflex of that private, complex, individual and highly personal process through which people cope with, and come to terms with, the vicissitudes of life.’
    • ‘That is to say, there are referential and quantificational uses of indefinite descriptions and these are a reflex of a genuine semantical ambiguity.’
    • ‘This individualism was perhaps a natural reflex of an economy bursting forth from its medieval limitations.’
    • ‘Her feet followed his automatically, as a reflex from many hour of being tortured in etiquette, posture, and dance classes.’
    1. 2.1 A word formed by development from an earlier stage of a language.
      • ‘Orza is the Italian reflex of a common Romance word generally thought to be of Latin origin.’
  • 3archaic A reflected source of light.

    ‘the reflex from the window lit his face’


  • 1(of an action) performed without conscious thought as an automatic response to a stimulus.

    ‘sneezing is a reflex action’
    • ‘In the respiratory tract, complex reflex responses to the gastric refluxate occur in children by three mechanisms.’
    • ‘Even the tears that fell were automatic, more a reflex action than reflection of any real emotion.’
    • ‘Hold fast - put one of your fingers in your baby's palm and enjoy his reflex response as he grips it tightly.’
    • ‘A cough is a reflex action to clear the airways of mucus, phlegm, irritants or a foreign body.’
    • ‘What he found was that every bird in a particular species has certain inflexible patterns of behavior, reflex responses to very specific stimuli.’
    • ‘The inhibitor of nitric oxide synthase failed to inhibit this response, and it also did not potentiate the reflex cholinergic contractions of the trachea produced by bradykinin.’
    • ‘The tongue directs the bolus of chewed food to the pharynx as an initial step in the involuntary reflex swallowing mechanism.’
    • ‘The mechanism by which the body senses and responds to changes in blood pressure by reflex vasodilation or contraction of peripheral vessels is impaired.’
    • ‘Almost as if it were a reflex response, journalists and some scientific researchers alike blame technology and changes to family life for childhood obesity.’
    • ‘The active ingredients in this were alkaloids of belladonna, which we now know had the effect of inhibiting cholinergic neurotransmission and thereby reflex bronchoconstriction.’
    • ‘So in some quarters the reflex response to the presidential election of November 2004 has been to emphasise how little has changed.’
    • ‘In a reflex action the body cuts the supply of blood to the arms and legs preventing swimming, and people then sink and drown.’
    • ‘During the initial inflammatory phase of this process the muscle responds with a reflex spasm which is the tightness or knot you can feel.’
    • ‘We now know that this reflex response is initiated from the class of sensory receptors called muscle spindle receptors.’
    • ‘This suggests that reflex mechanisms are diminished during the transition to sleep.’
    • ‘Later it becomes a reflex action in response to the baby's cry or just by thinking about the baby or feeding.’
    • ‘It is a complex reflex response to the stimulation of the cough receptors of the lung.’
    • ‘Muscle spindles are primarily influenced by changes in length and are responsible for reflex contraction of the skeletal muscles in response to stretching.’
    • ‘The same event, however, can take place without a swallow as a reflex response to mechanical stimulation of the esophagus.’
    • ‘Certainly, the very rapid respiratory rates seen during the tidal breathing collection in some of the children in this study must be attributed to reflex or cortical responses to testing.’
    instinctive, automatic, mechanical, involuntary, knee-jerk, reflexive, impulsive, intuitive, spontaneous, unconscious, subliminal, unthinking, unpremeditated, unconditioned, untaught, unlearned, unintentional, unwitting, inadvertent, accidental
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  • 2(of an angle) exceeding 180°.

  • 3rare (of light) reflected.

    1. 3.1 Bent or turned backward.
    2. 3.2 (of a thought) directed or turned back upon the mind itself; introspective.
      ‘an act of consciousness is a reflex act with its own object, viz. the act of knowledge itself’


Early 16th century (as a noun denoting reflection): from Latin reflexus ‘a bending back’, from reflectere ‘bend back’ (see reflect).