1. deviating from the usual or proper course in conduct or opinion; eccentric; queer: erratic behavior.
  2. having no certain or definite course; wandering; not fixed: erratic winds.
  3. Geology. noting or pertaining to a boulder or the like carried by glacial ice and deposited some distance from its place of origin.
  4. (of a lichen) having no attachment to the surface on which it grows.
  1. an erratic or eccentric person.
  2. Geology. an erratic boulder or the like.

Origin of erratic

1325–75; Middle English < Latin errāticus, equivalent to errāt(us) (past participle of errāre to err) + -icus -ic
Related formser·rat·i·cal·ly, adverber·rat·i·cism, nounnon·er·rat·ic, adjective, nounnon·er·rat·i·cal·ly, adverbun·er·rat·ic, adjective
Can be confusederotic erratic exotic

Synonyms for erratic

Antonyms for erratic Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for erraticism


  1. irregular in performance, behaviour, or attitude; inconsistent and unpredictable
  2. having no fixed or regular course; wandering
  1. 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
  2. an erratic person or thing
Derived Formserratically, adverb

Word Origin for erratic

C14: from Latin errāticus, from errāre to wander, err
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for erraticism



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.

Online Etymology Dictionary, © 2010 Douglas Harper