DIRTY

• dirt‧y comparative dirtier, superlative dirtiest
• 1

  not clean

  covered in or marked by an unwanted substance [≠ clean]:
• a stack of dirty dishes in the sink
• How did you get so dirty?
• dirty clothes/washing/laundry
• She circled the bedroom, picking up dirty clothes.
• 2

  sex

  relating to sex, in a way that is considered immoral or unpleasant:
• kids telling dirty jokes
• a dirty magazine
• She looked at me as if I had said a dirty word.
• have a dirty mind British English (=think about sex a lot)
• dirty weekend British English (=a weekend when a man and woman who are not married to each other go away to have sex)
• 3

  bad/immoral

  used to emphasize that you think someone or something is bad, dishonest, or immoral:
• You're a dirty liar!
• a dirty fighter
• you and your dirty little deals
• do the dirty on somebody British English (=treat someone in a way that is unfair or dishonest)
• What a dirty trick!
• 4

   something is a dirty word

  if something is a dirty word, people believe it is a bad thing even if they do not know or think much about it[= swear word]:
• 'Liberal' has somehow become a dirty word in America.
• 5

   give somebody a dirty look

  to look at someone in a very disapproving way:
• Susan gave her brother a dirty look.
• 6

   dirty trick

  a dishonest or unfair action, especially done by a government, company, or organization:
• political dirty tricks
• 7

   wash your dirty linen/laundry

  also air your dirty laundryAmerican English to discuss something embarrassing or bad about yourself where everyone can see, know, or hear:
• The divorce has meant airing their dirty laundry in court.
• 8

   do somebody's dirty work

  to do an unpleasant or dishonest action for someone, so that they do not have to do it themselves:
• I'm not talking to him; you do your own dirty work!
• 9

   it's a dirty job, but someone has to do it

  used to say that something is unpleasant to do, but that it is necessary - often used humorously
• 10

  drugs

  American English informal containing or possessing illegal drugs
• 11

   dirty bomb

  a bomb that contains a radioactive substance which makes the bomb more dangerous than bombs containing only traditional explosives
• 12

  sport

  a dirty sports event is one in which people competing in the event have illegally used drugs to improve their performance:
• Many people think that the race has been a dirty event for years.
• —dirtily adverb
• WORD FOCUS: dirty 
• similar words: filthy, grubby, grimy, mucky British English, muddy,greasy, dusty, soiled, contaminated, polluted

Definition from the Longman Dictionary of Contemporary English
Advanced Learner's Dictionary.