butt
I
 /ˈbʌt/  noun  ,  pl   butts [  count  ]
  1 chiefly US, informal + sometimes impolite : the part of the body you sit on : buttocks
   He slipped and landed on his butt. [=(chiefly Brit) bum]
   These exercises will make your butt firmer.
   Why don't you get off your butt and do something? [=why don't you stop being so lazy and do something?]
  — used in informal phrases where ass might also be used
   Get your butt over here! [=come over here now]
   She really saved my butt. [=she helped me out of a difficult situation]
   He worked his butt off [=he worked very hard] to finish on time.
  2 : the thicker end of a weapon or tool
   the butt (end) of a rifle
  3 a : the end part of a cigarette or cigar that is not smoked
   a cigarette butt
  3 b informal : a cigarette
   She went out to buy some butts.
  kick butt — see kick, 1
 — compare butt, 2, butt, 4, butt, 6
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II
  noun  ,  pl   butts [  count  ]
  : a person who is treated badly or is made fun of — usually singular;
  — + of
   As a child, she was a clumsy girl who was the butt of everyone's jokes. [=people made jokes about her because she was clumsy]
 — compare butt, 1, butt, 4, butt, 6
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III
  verb  , butts, butt·ed, butt·ing
  : to hit or push (something) forcefully with the head
   [  + obj  ] A few punches were thrown, and then one boy butted the other before a teacher broke up the fight.
    She got butted by an angry goat.
   [  no obj  ] We saw the goat butt against the gate until it opened.
  butt heads
    chiefly US    informal   : to disagree about how something should be done
    They've butted heads over the issue a number of times.
  butt in [  phrasal verb  ]
     informal   : to get involved in something (such as a conversation or someone else's activities) especially in a rude way
    I realize you're trying to help, but I wish you wouldn't butt in. You're only making things worse.
    Sorry to butt in (on you) like this, but I need to ask you a question.
  butt out [  phrasal verb  ]
     chiefly US    informal   : to stop being involved in something (such as a conversation or someone else's affairs)
    This has nothing to do with you! I wish you would just butt out!
    They told me to butt out of the conversation.
 — compare butt, 5
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IV
  noun  ,  pl   butts [  count  ]
  : a forceful hit or push with the head
   a head butt in/to the ribs
 — compare butt, 1, butt, 2, butt, 6
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V
  verb  , butts, butted, butting
   US   : to place something right next to something else or to be right next to something else
   [  + obj  ] We laid the boards so that the ends were butted against the wall.
   [  no obj  ] The floorboards are weakest where they butt (against each other). [=where they meet, where the ends of the boards touch each other]
    The apartment building butts up against an old church.
 — compare butt, 3
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VI
  noun  ,  pl   butts [  count  ]
   Brit   : water butt
 — compare butt, 1, butt, 2, butt, 4