What is the symbol used to represent word which?

There isn't a specific symbol used to represent the word "which" in any standardized way.

However, there are some ways you can represent "which" symbolically:

* In formal logic and mathematics: You can use variables like "x" or "y" to represent things, and then use a symbol like "?" or a colon ":" to represent "which" in a context like "Which x has property y?".

* In programming: Some programming languages use keywords like "where" or "such that" to represent a similar concept to "which" when filtering data or selecting elements.

Ultimately, the best way to represent "which" depends on the specific context and purpose. If you're looking for a symbol for a specific situation, it's best to define it clearly beforehand so everyone understands what it represents.