- deviating from the usual or proper course in conduct or opinion; eccentric; queer: erratic behavior.
- having no certain or definite course; wandering; not fixed: erratic winds.
- Geology. noting or pertaining to a boulder or the like carried by glacial ice and deposited some distance from its place of origin.
- (of a lichen) having no attachment to the surface on which it grows.
- an erratic or eccentric person.
- Geology. an erratic boulder or the like.
- irregular in performance, behaviour, or attitude; inconsistent and unpredictable
- having no fixed or regular course; wandering
- a piece of rock that differs in composition, shape, etc, from the rock surrounding it, having been transported from its place of origin, esp by glacial action
- an erratic person or thing
late 14c., “wandering, moving,” from Old French erratique (13c.) and directly from Latin erraticus “wandering, straying, roving,” from erratum “an error, mistake, fault,” past participle of errare “to wander, err” (see err). Sense of “irregular, eccentric” is attested by 1841. The noun is from 1620s, of persons; 1849, of boulders. Related: Erratically.