It's very much live. It's the name of the symbol. It's sometimes used as a symbol to mean 'approximately', as in "~100 BC". It's used in IT as a symbol for a home folder on Unix-based systems and for pattern matching in other languages.

Regardless of the symbol's function in different domains, the symbol's name remains 'tilde'.

Maybe you don't use the word much but that really has nothing to do with the price of fish.