How do you define product-market-fit?

Nothing better than actual real numbers. So rate of first visits vs rate of usage numbers in google analytics. Page-views. Session length. Recurring visits etc.

I'm creating an MVP to define it.

Product-market fit is when a product perfectly meets the needs and desires of a specific market, creating strong demand and customer satisfaction. It's that sweet spot where your offering resonates so well with your target audience that they become avid users and advocates, driving sustainable growth and success.