reflex

/ˈrɛflɛks/
nounIntermediate
formal

an automatic, involuntary response to a stimulus, such as a muscle contraction or movement, triggered by a sensory input

The sudden loud noise caused a reflexive jump.

The person reacted instinctively to the loud noise.

💡

Reflexes are typically mediated by the spinal cord and do not involve conscious thought.

informal

a quick, instinctive reaction or response

She had a reflex to duck when she heard the crash.

She instinctively reacted by ducking at the sound of the crash.

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In informal usage, 'reflex' can describe any quick, automatic reaction, not just physiological responses.

Collocations

reflex actionan automatic physical responsereflex responsean involuntary reaction to a stimulus

Synonyms

Antonyms

Related Phrases

knee-jerk reactionphrase
an immediate, often unthinking response

💡Pro Tip

Medical vs. Informal Usage

In medical contexts, 'reflex' refers strictly to involuntary physiological responses. In everyday language, it can describe any quick, instinctive reaction.

Gold Rule

Reflex vs. Reaction

A reflex is an involuntary, automatic response, while a reaction can be conscious or unconscious.

📖Word Origin

From Latin 'reflexus', meaning 'bent back' or 'reflected', referring to the idea of a response being reflected back to the stimulus.

📝Usage Notes

In medical contexts, 'reflex' refers specifically to involuntary physiological responses. In everyday language, it can describe any quick, instinctive reaction.

Word Breakdown

re-
back
prefix
+
-flex
bend
root
English Dictionary