When does someone stop being a twink?

I've been thinking about this because I feel like the term "twink" is used in so many different ways.

Is it about age? Body type? Being skinny? Having a certain style? Having less body hair? Or is it more about the overall vibe someone gives off?

At what point does someone stop being a twink and become something else?

I'm curious what everyone thinks because I feel like the definition changes depending on who you ask.