Contronym

A contronym or contranym is a word with two opposite meanings. For example, the word original can mean "authentic, traditional", or "novel, never done before". This feature is also called enantiosemy, enantionymy (enantio- means "opposite"), antilogy or autoantonymy. An enantiosemic term is by definition polysemic (having more than one meaning).

A contronym is alternatively called an autantonym, auto-antonym, antagonym, enantiodrome, enantionym, Janus word (after the Roman god Janus, who is usually depicted with two faces), self-antonym, antilogy, or addad (Arabic, singular didd).

Denotations and connotations of words can drift or branch over centuries. An apocryphal story relates how Charles II (or sometimes Queen Anne) described St Paul's Cathedral (using contemporaneous English) as "amusing, awful, and artificial", with the meaning (rendered in modern English) of "amazing, awe-inspiring, and artistic."

Seeming contronyms can arise from translation. In Hawaiian, for example, aloha is translated both as "hello" and as "goodbye", but the essential meaning of the word is "love", whether used as a greeting or farewell. Similarly, 안녕 (annyeong) in Korean can mean both "hello" and "goodbye" but the central meaning is "peace". The Italian greeting ciao is translated as "hello" or "goodbye" depending on the context; the original meaning was "at your service" (literally "(I'm your) slave").