Moving or functioning rapidly and energetically; speedy: an animal that is quick enough to escape most predators. Learning, thinking, or understanding with speed and dexterity; bright: a quick mind. Perceiving or responding with speed and sensitivity; keen: quick reflexes. Reacting immediately and sharply: a quick temper. Occurring, achieved, or acquired in a relatively brief period of time: a quick rise through the ranks; a quick profit. Done or occurring immediately: a quick inspection. See Synonyms at fast1. Tending to react hastily: quick to find fault. Archaic Alive. Pregnant. Sensitive or raw exposed flesh, as under the fingernails. The most personal and sensitive aspect of the emotions: The remark cut her to the quick. The living: the quick and the dead. The vital core; the essence: got to the quick of the matter.