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3.
FLS
Fat Leg Syndrome. A woman with fat thighs and legs. Most likely fat ankles too.

--Taken from Ray and Norberto.
That girl has FLS!
by GMoney Musikbyg January 31, 2009
 
1.
FLS
FLS = First Line Support'ers.
Is nice people who help alot, in Forum's.
Helping n00b's, like live FAQ.
FLS = First Line Support
by Ohke November 14, 2006
 
2.
FLS
FL Studio or FruityLoops Studio is an instrumental/beat making program used by many professional producers to make music.
A: Deem001 uses FLS.
B: What's that?
A: FL Studio or FruityLoops Studio. :]
by TheGosuBox January 14, 2010
 
4.
FLS
Flu-Like Symptoms (fever, chills, headache, fatigue.)

The acronym is used heavily in the medical community. It has yet to have been thrown around wildly on television medical dramas, so it's not part of the pop-culture medical lexicon.
John has had FLS for three days now, I think he might have the flu!
by MeakPhronkey December 20, 2007
 
5.
1.)A vague, fake medical condition that sounds serious but actually means that you Feel Like Shit.

2.) often used to call out of work, to aviod someone you don't want to hang out with, etc.
"Dave can't come in today, his F.L.S. is acting up again."
by Klitzke May 18, 2008
 
6.
FLS
Short for Fat Leg Syndrome. Occurs when you wear boots that are too big and they give you the appearance of fat legs.
Liz wore size eleven boots that she got on sale, even though she's a size five. needless to say, it gave her FLS.
by lizisapiz March 10, 2010