Bringing some order to bear on unsupervised learning
"Internal Clustering Validation Measures" might be what you are looking for, but still there are many options e.g. https://doi.org/10.1109/ICDM.2010.35
"Internal Clustering Validation Measures" might be what you are looking for, but still there are many options e.g. https://doi.org/10.1109/ICDM.2010.35