reflex noun
ADJ. good, lightning, quick | poor | automatic | natural | conditioned
VERB + REFLEX trigger The rapid movement of an object towards the eye triggers the blink reflex. | control | sharpen, speed up The training is designed to sharpen the fighter's reflexes. | slow (down) Alcohol can slow your reflexes. | suppress | test The doctor tested her reflexes.
REFLEX + NOUN action, reaction Almost as a reflex action, I grab my pen as the phone rings.
PREP. by ~ Almost by reflex, he helped himself to a drink.
You can also check other dicts: reflex (English, 中文解释 ), wordnet sense, Collins Definition