I. ˈhe-tə-rə-ˌklīt noun
Date: 1580
1. : a word irregular in inflection ; especially : a noun irregular in declension
2. : one that deviates from common forms or rules
II. adjective
Etymology: Middle French or Late Latin; Middle French, from Late Latin heteroclitus, from Greek heteroklitos, from heter- + klinein to lean, inflect — more at lean
Date: 1598
: deviating from common rules or forms