unpredictable β not predictable; not to be foreseen or foretold: an unpredictable occurrence.
unreliable β not reliable; not to be relied or depended on.
inconsistent β lacking in harmony between the different parts or elements; self-contradictory: an inconsistent story.
irregular β without symmetry, even shape, formal arrangement, etc.: an irregular pattern.
changeable β Someone or something that is changeable is likely to change many times.
intermittent β stopping or ceasing for a time; alternately ceasing and beginning again: an intermittent pain.
uneven β not level or flat; rough; rugged: The wheels bumped and jolted over the uneven surface.
fitful β coming, appearing, acting, etc., in fits or by spells; recurring irregularly.
variable β apt or liable to vary or change; changeable: variable weather; variable moods.
abnormal β Someone or something that is abnormal is unusual, especially in a way that is worrying.
arbitrary β If you describe an action, rule, or decision as arbitrary, you think that it is not based on any principle, plan, or system. It often seems unfair because of this.
bizarre β Something that is bizarre is very odd and strange.
capricious β Someone who is capricious often changes their mind unexpectedly.
eccentric β deviating from the recognized or customary character, practice, etc.; irregular; erratic; peculiar; odd: eccentric conduct; an eccentric person.
mercurial β changeable; volatile; fickle; flighty; erratic: a mercurial nature.
uncertain β not definitely ascertainable or fixed, as in time of occurrence, number, dimensions, or quality.
unstable β not stable; not firm or firmly fixed; unsteady.
unusual β not usual, common, or ordinary; uncommon in amount or degree; exceptional: an unusual sound; an unusual hobby; an unusual response.
volatile β evaporating rapidly; passing off readily in the form of vapor: Acetone is a volatile solvent.
wayward β turned or turning away from what is right or proper; willful; disobedient: a wayward son; wayward behavior.
weird β involving or suggesting the supernatural; unearthly or uncanny: a weird sound; weird lights.
whimsical β given to whimsy or fanciful notions; capricious: a pixyish, whimsical fellow.
aberrant β Aberrant means unusual and not socially acceptable.
anomalous β Something that is anomalous is different from what is usual or expected.
desultory β Something that is desultory is done in an unplanned and disorganized way, and without enthusiasm.
devious β If you describe someone as devious you do not like them because you think they are dishonest and like to keep things secret, often in a complicated way.
dicey β Something that is dicey is slightly dangerous or uncertain.
directionless β the act or an instance of directing.
dubious β doubtful; marked by or occasioning doubt: a dubious reply.
idiosyncratic β pertaining to the nature of idiosyncrasy, or something peculiar to an individual: The best minds are idiosyncratic and unpredictable as they follow the course of scientific discovery.
iffy β full of unresolved points or questions: an iffy situation.
spasmodic β pertaining to or of the nature of a spasm; characterized by spasms.
strange β unusual, extraordinary, or curious; odd; queer: a strange remark to make.
stray β to deviate from the direct course, leave the proper place, or go beyond the proper limits, especially without a fixed course or purpose; ramble: to stray from the main road.
undirected β not directed; not guided: He wasted his time on undirected activity.
unnatural β contrary to the laws or course of nature.
vagarious β characterized by vagaries; erratic; capricious: a vagarious foreign policy.
