A swimsuit is an item of clothing designed to be worn for swimming. Swimsuits can be skin-tight or loosely fitting and range from garments designed to preserve as much modesty as possible to garments designed to reveal as much of the body as possible without actual nudity. They are often lined with a fabric that prevents them from becoming transparent when wet.

I quite fancy that girl now I have seen her in her day-glo one piece swimsuit.
by navyblue December 3, 2006
The Private Parts, which are housed under you underpants.
Penis, Vagina, Titties

"I want to touch her swimsuit area"
by B-rad Bo-dad January 4, 2009
The effect of seening someone in a swimsuit, underclothes, naked, ect. then losing the ability to look them in the eye, look at them the same or look at them with a straight face again.
"that picture of Tyler just totally gave me the Swimsuit Effect."
by Drea Alexandria December 30, 2009
When your mate cums in your underwear and then you chuck them on leaving the reminents of his seamen all over your crotch
Mate- *cums in underwear and puts them back in your drawer*
You- *go to drawer and put said underwear on* "oh mate left me a nice slippery swimsuit did ya!"
by Oldmate21 September 4, 2015
At the beach, when a guy is shirtless and his back and chest are covered with so much hair it looks like he's wearing a sweater!!
Nice swimsuit sweater!
by Lacielovestrex March 19, 2014
The term used to describe what people in the mafia would make their victims "wear" before swimming with the fishes. Usually consisting of weights/bricks/other heavy objects being attached to someone before being thrown into a large, deep body of water.
Mafia guy: Hey, this guy won't pay up.

Other guy: Well, let's give him an Italian Swimsuit because he's gonna be swimming with the fishes pretty soon.

Mafia guy: I'll go grab some bricks.
by Jukedalon May 2, 2010
A Relationship that forms usually in high school after one party sees the other in a somewhat revealing swimsuit.
I thought that kyle hated stacy, I never thought that they would go out." "Dude, It's just a swimsuit relationship.
by Oberservent June 12, 2010