The construction of these shorts is somewhat peculiar; it's rare to see such specific sizing on clothing items with "lounge" on it, but the size range is quite narrow.  Wife tried these on and compared to a similar Calvin Klein product she has.  The CKs are medium and fit fine for her size 8.  But these shorts have very fitted; the size M is very true to the chart size of 6.  In other words, too tight on her and ends up creating a muffin top.  But the 8 is an "XL", which seems crazy to me.

Other than that, she reports that the material is soft and comfortable, but definitely too small for her.  Be sure to use the chart as a guide.