I'm sure this is the sort of thing that most people do when they first learn to speak, rather than decades later. But I realised yesterday that I couldn't think of any words that had more than one opposite meaning.
That is: "good" has one opposite. Namely, "bad".
Likewise, the one opposite of "on" is "off".
Therefore, I was delighted this evening to realise that "lost" has two opposites: "won" and "found".
Now I think about it, I'm sure there are thousands of others. Presumably all one has to do is analyse every heteronym in the language.
Still... I enjoyed my victory.
(Now I think about it, it's not obvious that "on" only has one opposite. Presumably "under" is also valid. I suppose I should be pleased to have found another. But I'm actually a little irritated that it's so easy to find them)