(adj): vs. slow) -- (acting or moving or capable of acting or moving quickly
(adj): hurried and brief
(adj): vs. unhurried) -- (moving rapidly or performed quickly or in great haste
(adj): moving quickly and lightly
(adj): vs. inactive) -- (characterized by energetic activity
(adj): apprehending and responding with speed and sensitivity
(adj): vs. unintelligent) -- (having the capacity for thought and reason especially to a high degree
(adj): performed with little or no delay
(adj): vs. slow) -- (acting or moving or capable of acting or moving quickly
(adj): easily aroused or excited
(adj): vs. unexcitable) -- (easily excited
(n): any area of the body that is highly sensitive to pain (as the flesh underneath the skin or a fingernail or toenail)
(n): a part of an animal that has a special function or is supplied by a given artery or nerve
(adv): with little or no delay
alive, as the quick and the dead, or as cut to the quick
Contronymic in the sense: fleet vs. fixed center.