1. (使)变粗糙
If something coarsens or is coarsened, it becomes thicker or rougher in texture.

2. (使)变粗俗;（使）变粗鲁
If someone's behaviour or speech coarsens or if they coarsen it, they become less polite or they begin to speak in a less pleasant way.

1. make less subtle or refined

e.g. coarsen one's ideals

2. make or become coarse or coarser

e.g. coarsen the surface
Their minds coarsened