Meaning of REFLEX in English
/ 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.
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. 2005