Incrassation refers to thickening or growing thicker. Antonyms for this word include thinning, reducing, slimming down, or decreasing. If we talk about reducing the thickness of something, antonyms for incrassation can be dilution, thinning, or reducing in density. When it comes to the slimming down of body fat, antonyms could be weight loss, weight reduction, and fat reduction. Similarly, in terms of decreasing the thickness of some material, antonyms for incrassation will include decreasing, flattening, or compressing. Whatever the context, antonyms for incrassation are all about decreasing or slimming down, rather than increasing or growing thicker.