Restless, a. — Webster enters it under “restless”
Etymology: [AS. restleás.]
1. Never resting; unquiet; uneasy; continually moving; as, a restless child. Chaucer. "Restless revolution day by day." Milton.
2. Not satisfied to be at rest or in peace; averse to repose or quiet; eager for change; discontented; as, restless schemers; restless ambition; restless subjects. "Restless at home , and ever prone to range." Dryden.
3. Deprived of rest or sleep. Restless he passed the remnants of the night. Dryden.
4. Passed in unquietness; as, the patient has had a restless night.
2 more senses
5. Not affording rest; as, a restless chair. Cowper. Restless thrush. (Zoöl.) See Grinder, 3.
Syn. -- Unquiet; uneasy; disturbed; disquieted; sleepless; agitated; unsettled; roving; wandering. -- Rest"less*ly, adv.- Rest"less*ness, n.
Shades of meaning
Fernald lists restlessness only as an antonym, under rest.
He lists it without comment; the entries above explain its neighbors.