look up any word, like sapiosexual:
 
15.
si
Abbr. Simple Simon. Individual renowned for extreme stupidity and slowness of mind.
"Jog on you si - you're as thick as pigshit" or "he's a proper si that one, thicker than a King Edward yoghurt"
by Phileas May 20, 2008
36 62
 
16.
SI
self injury.

cutting, carving, bruising, welting, etc.
you: damn... i hate emos.
me: ......
you: you SI?!?
me: ......
by 341103001 August 22, 2007
27 56
 
17.
SI
1. Spanish for "yes."
2. Misspelling of "is."
1. "I suck." "Si."
2. "NO YUO FAGOT A COMPUTAR SI NOT A HAT!"
by Dj gs68 September 22, 2003
81 111
 
18.
SI
Organization of sensation for use.
A type of therapy effective for children with processing disorders including autism.
therapists facilitate a child's intrinsic understand of body sensations to better interact with the understanding of everything that is not the body
by occupational therapist December 14, 2004
5 36
 
19.
SI
Sports Illustrated
I done read SI.
by Andy L August 03, 2003
15 46
 
20.
SI
Abbreveation of Science and Industry, possibly the most popular Half-Life mod around.
'I'm sorry mum, i can't go and have a bath, im going to play SI'

'I'd rather play SI than CS'
by Anonymous June 26, 2003
3 34
 
21.
Si
An unbelievably rich cunt (richer than Bill Gates) who wears a monacle and probably has other characteristics but none you really care about.

Also likes boys and sniffing the sweatline under fat guys flabbing man breasts.
Brian has loads of money for beer tonight. He could do a Si and buy the pub free drininks all night.
by Bobby Charlton March 18, 2004
17 49