grind down

English

grind down (third-person singular simple present grinds down, present participle grinding down, simple past and past participle ground down)

(transitive) To make something hard smaller and smoother by gradually rubbing off tiny bits; to wear down by grinding action.
The old dog's teeth had been ground down by constant use.
(idiomatic, transitive) To weaken someone's morale over a long period.
- 2018 July 15, Jonathan Jurejko, “Novak Djokovic wins fourth Wimbledon by beating Kevin Anderson”, in BBC Sport‎^[1]:
  Djokovic broke twice in each of the opening two sets, dismantling 6ft 8in Anderson's service game and grinding him down in the rallies.
- 1997, The Toasters, Don't Let the Bastards Grind You Down:
  I'm living in a world where I don't really fit
  Every day walking through the same old shit
  I'm gonna get my gun, gonna get prepared
  I'm not impressed and I'm not scared
  Don't let the bastards grind you down!
  Don't let them grind you down!
  Don't let the bastards grind you down!
  Don't let them grind you down!

to wear down