The Oxford Thesaurus An A-Z Dictionary of Synonyms - erratic adj.

1) irregular, unpredictable, inconsistent, unreliable, capricious, changeable, variable; wayward, unstable, aberrant, flighty: The buses run on an erratic schedule. 2) peculiar, abnormal, wayward, odd, eccentric, outlandish, strange, unusual, unorthodox, extraordinary, queer, quaint, bizarre, weird, unconventional: He thinks that his erratic behaviour marks him as an individualist. 3) wandering, meandering, directionless, planetary, aimless, haphazard, discursive, errant, divagatory: Their course was erratic, following the loss of their compass.