tar
I
 /ˈtɑɚ/  noun  ,  pl   tars [  count  ,  noncount  ]
  1 : a very thick, black, sticky liquid made from coal that becomes hard when it cools and that is used especially for road surfaces — see also coal tar
  2 : a sticky substance that is formed by burning tobacco
   low-tar cigarettes
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II
  verb  , tars, tarred, tar·ring [  + obj  ]
  : to cover (something) with tar
   tar a roadway
  tar and feather (someone)
   1 : to cover (someone) with tar and then with feathers as an old-fashioned punishment
   2 informal : to punish (someone) very severely
    If I don't get home in time, Mom will tar and feather me.
  tar (someone) with the same brush
   : to think that (someone) has the same bad qualities and deserves the same blame or criticism as another person because of being connected or associated with that person in some way
    It's a shame that when a few people get caught cheating everyone else gets tarred with the same brush.