look up any word, like cunt:
 
1.
ISL
The Independent School League, also known as the ISL is a league of 16 relatively small New England Prep schools. The ISL has some of the best schools in the United States, most notably The Groton School, Middlesex School, and Roxbury Latin School, among others. The ISL is also well know for its strong athletics, especially in Football, Hockey, and Basketball.
Just because the ISL schools are smaller, doesn't mean they cant hold their own with the larger schools like Pillips Andover, and Chotae.
by F.I.S.T.14 October 04, 2009
 
2.
ISL
ISL: An abbreviation to "I Silently Laugh " this is used because 99.99% of the time one will send "LOL" they are not actually, laughing out loud.
*text msg*

Brandon: OMG did you see that video with the dogs leg stuck in the toilet
Jack: ISL YES!!!
by MGnT1999 November 20, 2013
 
3.
isl
A group of private schools in Massachusetts (The Roxbury Latin School, Thayer Academy, Belmont Hill School, et al.) of which RL is the smallest and most respected.
You go to an ISL school? Hope it's not Nobles.
by brainbrain July 05, 2006
 
4.
isl
An instant messaging acronym meaning "I seriously lol'd."
This came about after lol was becoming over used and needed a more accurate word
"isl" can be used if someone says something that acually did make you laugh out loud
by Zack A September 27, 2005
 
5.
ISL
The Independant School League

A league of prep schools in N.E. that basically live to make fun of everyone else...ie, all hate public schools in unity, and then each school hates every other school too...a sad circle of false unity spread by lies and false faces, actuality, a group of individuals with temporary allies and enemies...
Milton Academy, of the ISL, played and smoked Nobles in football again...
by Mustang April 24, 2005
 
6.
ISL
Ugh.... a group of prep-schools in New England, surrounding Boston. Thayer Academy is the only one that remotely resembles an actual highscool.
"ISL football is a joke. Nobles sucks. Milton needs to get that giraffe out of their ass."
by Arrbear December 31, 2004