dress down in WordNet English dictionary

1. censure severely or angrily
   "The mother scolded the child for entering a stranger's car"; "The deputy ragged the Prime Minister"; "The customer dressed down the waiter for bringing cold soup"
   call on the carpet  take to task  rebuke  rag  trounce  reproof  lecture  reprimand  jaw  dress down  call down  scold  chide  berate  bawl out  remonstrate  chew out  chew up  have words  lambaste  lambast 
   
2. dress informally and casually
   "On Fridays, employees can underdress"
   dress down  underdress 
   

dress down in English Wiktionary