Landing : Athabascau University

Contronyms: words that mean the opposite of what they mean.

http://www.dailywritingtips.com/75-contronyms-words-with-contradictory-meanings/

"The English language includes an interesting category of words and phrases called contronyms (also spelled contranyms, or referred to as autoantonyms) — terms that, depending on context, can have opposite or contradictory meanings. When you use these words, be sure the context clearly identifies which meaning is intended."