This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

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v. Present participle of coarsen.

"As a result, you should expect to be smacked down smacked down — hard — if only for your reckless, juvenile role in coarsening debate in a blogosphere that is already more than coarse enough, thank you."

coarsened    coarsening    coarsens   

change    modify    alter   

roughen    sensualize