re·flex  (r??fl?ks?)adj.1. Physiology Being an involuntary action or response, such as a sneeze, blink, or hiccup.2. Produced as an automatic response or reaction: reflex opposition to change.3. Bent, turned, or thrown back; reflected.4. Reflexed.n.1. a. Physiology An involuntary response to a stimulus.b. reflexes A person’s ability to respond to new or changing stimuli: His quick reflexes make him a good taxi driver.2. Psychology An unlearned or instinctive response to a stimulus.3. Linguistics A form or feature that reflects or represents an earlier, often reconstructed, form or feature having undergone phonetic or other change.4. a. Something, such as light or heat, that is reflected.b. An image produced by reflection.c. A copy or reproduction.[From Middle English reflexen, to refract light, bend back, from Latin reflexus, past participle of reflectere, to bend back; see reflect.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.reflex n 1. (Physiology) a. 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 stimulusb. (as modifier): a reflex action. See also reflex arc 2. (Psychology) a. a mechanical response to a particular situation, involving no conscious decisionb. (as modifier): a reflex response. 3. (General Physics) a reflection; an image produced by or as if by reflection 4. (Linguistics) a speech element derived from a corresponding form in an earlier state of the language: “sorrow” is a reflex of Middle English “sorwe”. adj 5. (Mathematics) maths (of an angle) between 180° and 360° 6. (prenominal) turned, reflected, or bent backwards vb (tr) to bend, turn, or reflect backwards [C16: from Latin reflexus bent back, from reflectere to reflect] re?flexible adj re?flexi?bility nCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014re?flex (adj., n. ?ri fl?ks; v. r??fl?ks) adj. 1. 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 or color. 4. bent or turned back. n. 5. a. Also called re?flex act`. movement caused by a reflex response. b. Also called re?flex ac`tion. the entire physiological process activating such movement. 6. any automatic, unthinking, often habitual behavior or response. 7. the reflected image of an object. 8. a reproduction, as if in a mirror. 9. a copy; adaptation. 10. reflected light, color, etc. 11. an element in a language, as a sound, that has developed from a corresponding element in an earlier form of the language: The(?)in stone is a reflex of Old English ?. v.t. 12. to subject to a reflex process. 13. to bend, turn, or fold back. [1500?10;