Other forms: reflexes
A reflex is the instant body reaction that happens before you can think. The hand is off the hot pan already.
The signal never reaches the brain first, which is the whole point, since it travels to the spinal cord and back and saves the fraction of a second that matters. Doctors test the knee reflex because a missing one says something about the nerves. Sport uses the plural for speed of reaction, so a goalkeeper with quick reflexes. A reflex action is one you cannot choose.
A reflex is a bending back. Latin reflectere is re, back, plus flectere, to bend, so the response turns straight round and comes back at you without asking.
Latin
reflexus
English, today
reflex
Built from
From Latin reflexus, past participle of reflectere (“to bend back”), equivalent to re- + flex. Photography sense is from noun sense meaning “reflection”. Compare English reflect.
Etymology from Wiktionary, CC BY-SA