Contronyms

[schnee]

Today I learned that words that have different, opposite meanings are called contronyms (thanks Merriam-Webster). The example that MW give is sanction; other examples, from Wikipedia, include to clip (which can indicate both removal and fastening) and oversight. (Wikipedia actually lists a bunch more, several of which I find questionable, or even incorrect, especially in languages other than English.)

I'd also list inflammable, which can mean both flammable and (perhaps) nonflammable. See this entry.