[ adjective, noun ree-fleks; verb ri-fleks ]
/ adjective, noun ˈri flɛks; verb rɪˈflɛks /



verb (used with object)

Origin of reflex

1500–10; < Latin reflexus bent back, past participle of reflectere to reflect
Related formsre·flex·ly, adverbre·flex·ness, nounmul·ti·re·flex, nounsem·i·re·flex, noun Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for reflex

British Dictionary definitions for reflex


noun (ˈriːflɛks)

adjective (ˈriːflɛks)

maths (of an angle) between 180° and 360°
(prenominal) turned, reflected, or bent backwards

verb (rɪˈflɛks)

(tr) to bend, turn, or reflect backwards
Derived Formsreflexible, adjectivereflexibility, noun

Word Origin for reflex

C16: from Latin reflexus bent back, from reflectere to reflect
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for reflex



c.1500, "reflection of light," from verb reflex meaning "refract, deflect" (late 14c.), from Late Latin reflexus "a bending back," noun use of past participle of reflectere (see reflection). Meaning "involuntary nerve stimulation" first recorded 1877, from reflex action (1833).

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for reflex


[ rēflĕks′ ]



Being an involuntary action or response, such as a sneeze, blink, or hiccup.
Bent, turned, or thrown back; reflected.


To cause to undergo a reflex process.
To reflect.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for reflex


[ rēflĕks′ ]

An involuntary physiological response to a stimulus, as the withdrawal of a body part from burning heat.
An unlearned or instinctive response to a stimulus. Also called unconditioned response See more at classical conditioning.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Culture definitions for reflex


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.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.