|Definition - A word that can mean two opposite things.|
Example - The word cleave can mean both "to join together" and "to break apart."
Note: The two distinct meanings for cleave exist because the word is actually two distinct words that entered English at different times but which have evolved to have the same spelling. The join-together cleave derives from the Old English clifian, adhere, whereas the split-apart cleave derives from the Old English cleofan, to split.
Etymology - The word contranym was probably coined by combining contra (which in Latin means "against") with the Greek-derived combining form nym (from the Greek onyma, name).
Note: There are claims floating around the internet that the term was coined by either Joseph T. Shipley or Jack Herring, but no one has offered up any proof for this. This claim — which I believe started with the Wikipedia — has been copied and recopied by multiple "information" sites, such as answers.com, so much so that it now seems to have a thick layer of corroboration encasing it, when in fact it is just the same unverified claim being repeated over and over again.