When I was first learning english, I thought 'dust' (verb) actually only meant "to sprinkle dust on/over something", and I was shocked to find out that it also means the opposite (ie.to remove dust)!
The same with some others such as cleave, buckle, etc.
And when I was in Boston, I often heard bostonians said "irregardless" with such thick boston accent, which surprised me because I knew that the word does not actually exist, "regardless" is the correct form.