an action or a movement of your body that happens naturally in response to something and that you cannot control; something 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. 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’.Extra examples Almost as a reflex action, I grab my pen as the phone rings. Almost by reflex, he helped himself to a drink. He reacts with lightning fast reflexes. The rapid movement of an object close to the eye triggers an automatic reflex. The training is designed to sharpen the fighter’s reflexes.