What does ∼ mean?

“∼” is one of many symbols, listed in the Wikipedia article on approximation, used to indicate that one number is approximately equal to another. Note that “approximately equal” is reflexive and symmetric but not transitive. “∼” is one of many symbols used in logic to indicate negation.

What is tilde used to represent?

As a mathematical symbol, the tilde means “approximately” and in logic it means “not.” The tilde is one of the 128 alphanumeric and special characters in ASCII, the most common standard for electronic text exchange.