Synonyms for Erratic:

adj.

agitated (adjective)
feverish, shuddering, jerky, shivering, spastic, nervous, upset, Churned, writhing, quavering, shaking, quivering, shaken, palpitating, disturbed, quaking, perturbed, restless, convulsive, Jarred, wobbling, twitchy, disquieted, jittery, jumpy, trembling, unquiet, agitated, fluttered, troubled, distraught, twitching, skittish, uneasy.
all (adjective)
wandering, mercurial, temperamental, quicksilver, fickle, planetary.
capricious (adjective)
fleeting, whimsical, wayward, indecisive, flighty, capricious, impulsive, sporadic, frivolous, scatterbrained, fitful, Flitting, quirky, fly-by-night, volatile, fanciful, vacillating, random, fickle, changeful, arbitrary, fluctuating, changeable.
changeable (adjective)
unpredictable, inconstant.
irregular (adjective)
fluctuating, asymmetric, unsystematic, uneven, irregular, sporadic, jerky, variable, desultory, capricious, intermittent, eccentric, inconstant, unrhythmical, fitful.
irresolute (adjective)
halfhearted, undecided, hesitant, uncertain, unresolved, infirm, weak, Shilly-shally, Flitting, shifty, tentative, shrinking, spineless, insipid, fly-by-night, irresponsible, irresolute, shy, capricious, dillydallying, yellow, inconsistent, changeable, impulsive, indecisive, unsure, watery, ambivalent, double-minded, unwilling, fickle, vacillating, undependable, volatile.
itinerant (adjective)
wandering.
nonconforming (adjective)
curious, crosspatch, fey, uncommon, deviant, strange, eccentric, novel, odd, different, incongruous, funny, improper, extraordinary, abnormal, idiosyncratic, unfamiliar, un-ordinary, atypical, irregular, aberrant, outlandish, incompatible, misfit, deranged, nonconforming, uncustomary, oddball, anomalous, bizarre, inconsistent, unconventional, untypical, peculiar, oddity, freakish, exceptional, crazy, unusual, quirky, divergent, singular, off, out of the ordinary, unique, mismatch.
temperamental (adjective)
temperamental.
unpredictable; wandering (adjective)
capricious, fitful, unnatural, eccentric, planetary, inconsistent, peculiar, abnormal, idiosyncratic, strange, mercurial, inconstant, devious, irregular, oddball, changeable, weird, stray, variable, unusual, uncertain, bizarre, unstable, wayward, anomalous, arbitrary, aberrant, volatile, unreliable, desultory, whimsical.

n.

floating, brief, short-term, short-lived, passing, temporary, transient. aimless. devious, purpose, stray. same, unsteady, patchy, continue, spotty. ticklish, unstable, fantastical, change, unpredictable. erratic (noun)
fickle, unsettled, quicksilver, unreliable, undependable, planetary, temperamental, mercurial, wandering, changeable, changeful.
variable (noun)
unpredictable, aimless.

Other synonyms:

kooky. patchy, rum, unpredictable, spotty. cranky, fantastical, weird, unnatural. ticklish, devious. unstable. inconstant
unsteady.
purposeless
aimless.

Usage examples for erratic

  1. I don't mean bad- tempered, but seldom anything but erratic – Antony Gray,--Gardener by Leslie Moore
  2. It was that of Mr. Stead, the erratic Editor first of the Pall Mall and then of the Review of Reviews. – The Adventure of Living by John St. Loe Strachey
  3. At such times the trick mule was wont to do the most erratic things. – The-Circus-Boys-on-the-Flying-Rings-or-Making-the-Start-in-the-Sawdust-Life by Darlington, Edgar B. P.