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1. Liable to sudden unpredictable change
   "erratic behaviour"
   - fickle, mercurial, quicksilver
    
2. Having no fixed course
   "an erratic comet"
   - planetary, wandering
    
3. Likely to perform unpredictably
   "erratic winds are the bane of a sailor"
   - temperamental

1. (geology) a boulder of rock that differs from the surrounding bedrock because it has been transported by a glacier

Derived forms: erratics

See also: changeable, changeful, erratically, undependable, unreliable, unsettled

Encyclopedia: Erratic