Definition of erratic

< errata

erratum >

er·rat·ic    (-rtk) KEY 

ADJECTIVE:

1. Having no fixed or regular course; wandering.
2. Lacking consistency, regularity, or uniformity: an erratic heartbeat.
3. Deviating from the customary course in conduct or opinion; eccentric: erratic behavior.

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ETYMOLOGY:
Middle English erratik, from Old French erratique, from Latin errticus, from errre, to wander; see ers- in Indo-European roots

OTHER FORMS:
er·rati·cal·ly(Adverb), er·rati·cism  (--szm) KEY (Noun)