/ ˈkɔːsn; NAmE ˈkɔːrsn/ verb
1.
to become or make sth become thicker and/or rougher :
[ v ]
Her hair gradually coarsened as she grew older.
[ vn ]
His features had been coarsened by the weather.
2.
to become or make sb become less polite and often offensive in the way they behave :
[ vn ]
The six long years in prison had coarsened him.
[also v ]