Meaning of REFLEX in English

REFLEX

/ ˈriːfleks; NAmE / noun

an action or a movement of your body that happens naturally in response to sth and that you cannot control; sth that you do without thinking :

The doctor tested her reflexes.

to have quick / slow reflexes

a reflex response / reaction

Only the goalkeeper's reflexes (= his ability to react quickly) stopped the ball from going in.

Almost as a reflex action , I grab my pen as the phone rings.

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WORD ORIGIN

early 16th cent. (as a noun denoting reflection): from Latin reflexus a bending back, from reflectere bend back, from re- back + flectere to bend.

Oxford Advanced Learner's English Dictionary.      Оксфордский английский словарь для изучающик язык на продвинутом уровне.