adj. Bent, turned, or thrown back; reflected.adj. Physiology Being an involuntary action or response, such as a sneeze, blink, or hiccup.adj. Produced as an automatic response or reaction: reflex opposition to change. n. Something, such as light or heat, that is reflected.n. An image produced by reflection.n. A copy or reproduction.n. Physiology An involuntary response to a stimulus.n. Psychology An unlearned or instinctive response to a stimulus.n. Linguistics A form or feature that reflects or represents an earlier, often reconstructed, form or feature having undergone phonetic or other change.v. To bend, turn back, or reflect.v. To cause to undergo a reflex process.