From BiblePortal Wikipedia

Vine's Expository Dictionary of NT Words [1]

1: Ἀκατάστατος (Strong'S #182 — Adjective — akatastatos — ak-at-as'-tat-os )

"unsettled, unstable, disorderly" (a, negative, kathistemi, "to set in order"), is translated "unstable" in  James 1:8; "restless" in  James 3:8 , RV [in the latter, the AV "unruly" represents the word akataschetos, signifying "that cannot be restrained" (a, negative, katecho, "to hold down, restrain"). In the Sept.,  Job 31:11 .]. See Unruly , Unstable. In the Sept.,   Isaiah 54:11 .

Webster's Dictionary [2]

(1): ( a.) Deprived of rest or sleep.

(2): ( a.) Not affording rest; as, a restless chair.

(3): ( a.) Never resting; unquiet; uneasy; continually moving; as, a restless child.

(4): ( a.) 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.

(5): ( a.) Passed in unquietness; as, the patient has had a restless night.