Noun

1. Unflattering facts or questionable activities that one wants to remain secret, but which some other may use to blackmail with.

   If you don't tell me why you did it, I'll air all your dirty laundry to your boss.

2. Laundry that is unclean or soiled

   If you bring your dirty laundry round on Saturday, I'll wash it for you.

3. A clothes hamper or other container used to place unclean or soiled laundry.

   Place your dirty clothes in the dirty laundry.