A Janus word is a word that means both a thing (or an action) and its precise opposite. The name is a reference to Janus, a Roman god with two faces. If you didn’t catch that reference without it being explained, you probably aren’t very interested in this blog.
Some examples:
- Sanction
- Seed
- Weather
here are some other examples and longer discussions:
http://mentalfloss.com/article/49834/14-words-are-their-own-opposites
