1. short for "lunatic". A crazy person. This term is derived from the phrase "crazy as a loon".

2. in Canada this word denotes a 1 dollar coin that has a loon bird on one side. A Canadian 2 dollar coin, which has a polar bear on one side is called a "toony".
1. The loony is on the grass.

2. At the University of Toronto I talked to a student there and I mentioned seeing the word "loonies" on a video game in a bar nearby. I told her that in America a loony is a lunatic, that the word means that someone is nuts. She said it used to mean that in Canada too, but the meaning changed when the coins were introduced.
by I Saw U2 Live Twice May 12, 2007
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Another name for Luna Lovegood from Harry Potter. It's a nickname that she got from being so quirky.
Peeves:Potter luuuuurves Loony!
by Jedi Master Luna February 3, 2006
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Someone who thinks they are effected by the phases of the moon - especially a full moon
You must be a loony
by Mike P January 21, 2004
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A Canadian dollar coin, so named, because it has the image of a wild loon on its face, and Queen Elizabeth on the other, it's hard to tell which is which.
Shoot me a loonie for a pop, I'm thirsty.
by Canadian prick December 22, 2003
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Goofy, crazy.

I guess it could also mean 'like a loon (the bird)', but what would that be saying?
Mick: Steve's acting a little loony; now he's always talking about this get-rich quick scheme that he brought home from work and how he really wants each of us to have a piece of it. I'm not sure if he's joking or what.

Stan: You can never tell with that guy.
by Diggity Monkeez May 27, 2005
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