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1.
I little piece of plastic and metal that sits in your mouth after the removal of Braces. Can easily get lost for they are often translucent, and are highly enjoyed by dogs as a tasty snack.
"Sorry, My dog ate my retainers."
by Plasticine June 06, 2005
 
2.
A piercing stud, generally clear, used to hold a pierced hole open so as not to be seen by others. Commonly used for hiding a piercing during work and interviews.
A : "And do you have any piercings?"
B : "Well can you see any?"
A : "No I can't"
B : "Then nope"

-Later-

C : "So did they see your piercings?"
B : "Nope, Thank goodness we got me these retainers"
by Afterrhythmia March 15, 2009
 
3.
1 a fee paid to a lawyer or professional adviser for advice or services or to ensure that he/she will act on one's behalf if needed

2 a fee paid regularly to a freelance journalist to ensure that his/her services will be available when required

I have given John a retainer to make sure he will take on my case.
by Heath 2 July 07, 2006
 
4.
a code word for butt plug when involiving a queer bag
josh loves retainers in his ass
by jo00000on August 19, 2006