The adjective erratic describes things that are unpredictable, unusual, and that deviate from the norm. An erratic quarterback might completely confuse his receivers waiting for a pass.

Like its linguistic relative, error, the adjective erratic means "deviating from the norm," or "wrong." It also implies behavior or qualities that are unpredictable or odd. The word comes from the Latin verb errare, or "to wander" off course. In the field of geology, a rock that is erratic is unlike others in its environment because it has been transported by glacial activity. Likewise, someone driving a car that veers out of its lane is said to be driving erratically.

Definitions of erratic

adj liable to sudden unpredictable change

erratic behavior”
fickle, mercurial, quicksilver
changeable, changeful
such that alteration is possible; having a marked tendency to change

adj likely to perform unpredictably

erratic winds are the bane of a sailor”
undependable, unreliable
not worthy of reliance or trust

adj having no fixed course

“an erratic comet”
planetary, wandering
not settled or established

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