adjective • (of a person) unable to keep still or silent and becoming increasingly difficult to control, esp. because of impatience, dissatisfaction, or boredom. • (of a horse) refusing to advance, stubbornly standing still or moving backward or sideways.
ORIGIN late 16th cent.: from Old French restif, -ive, from Latin restare ‘remain.'. The original sense, [inclined to remain still, inert] has undergone a reversal; the association with the refractory movements of a horse gave rise to the current sense [fidgety, restless].
Some days I feel like the “of a person” version, and some days like the “of a horse” version. “Impatience, dissatisfaction, or boredom” coupled with “refusing to advance” and “stubbornly standing still.” Bah.
(Dictionary definition shamelessly copied from the Oxford American Dictionary which ships with every Apple computer these days.)