They claim to know that words are being used wrongly, but they don’t know that if someone claims the words they are using mean some particular thing, that person is right, because that is what they meant by those words.

For example, Freedom of Speech is often used as a synonym for Freedom of Expression, which is the idea that an open environment for public discussion is valuable to society and merits some kind of respect or protection, legal or otherwise. Instead of arguing that an open environment for public discussion is not worth having or otherwise necessary or preferable to do without, people sometimes instead try to make the accusation that people who are pro-free-expression are stupid because of not understanding what words mean.