[noun] [C] - an uncontrollable physical reaction to somethingThe doctor hit me just below the knee to test my reflexes.Psychologists have studied conditioned reflexes (= reactions which are learned rather than natural) in people and animals for over a hundred years.I'm sorry I punched him, it was a reflex action/response.
REFLEX
Meaning of REFLEX in English
Cambridge English vocab. Кембриджский английский словарь. 2012