This might be a bit of professional bias on my part but I like to think of product-market fit using ideas inspired by information theoretic model-data fit: Low

This might be a bit of professional bias on my part but I like to think of product-market fit using ideas inspired by information theoretic model-data fit: Low resolution fit: The product vaguely and simply fits its market. High resolution fit: The product is complex and is tightly tailored to the market. Overfit: The product is so tightly tailored to some users that it only fits well a small part of the market. Underfit: The product is so generic that it's easy to copy or is missing important features. Then it becomes about trying to achieve optimal fit. It's almost a bayesian thing in my mind. You want a product or platform that is not overfitted, not underfitted, high resolution where it needs to be, low resolution otherwise. There is one more dimension I find useful which I will call "crossfit" because it is inspired from the concepts of cross entropy (https://en.wikipedia.org/wiki/Cross_entropy https://en.wikipedia.org/wiki/Cross_entropy) or KL divergence (https://en.wikipedia.org/wiki/Kullback%E2%80%93Leibler_divergence https://en.wikipedia.org/wiki/Kullback%E2%80%93Leibler_diver...). Having bad crossfit means that the product fit is biased in some suboptimal way. It might fit a side market of a greater market, it might focus on aspects that would be more important in another market or it might use a design language that is better tailored to different users. Having bad crossfit often happens when product teams with expertise in one domain apply their knowledge to a second domain without being sufficiently familiar with the differences. Without taking into account differences in key details of the new domain, without learning the new lingo or without properly weighting the different levels of importance of challenges, product fit tends to end up not quite right. An extreme but common example is that of software developers (like myself) designing interfaces that are very difficult to use for anyone but other software developers. However, it can also happen in subtler ways even for experienced product designers when they jump into a new field they are not very familiar with. Having good crossfit is about learning to speak the language of your users.