si 

derogatory term for man who thinks hes a fox.

si, you isnt a fox dude!

si by kezza January 30, 2005

SI 

Level Trim for Honda Civic and etc... it means.. SLOW IMPORT..

That SI got beat by my geo.

SI by HawkINX4 April 14, 2004

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

SI by occupational therapist December 14, 2004

si 

Abriviation for suck it, normally used on MMORPG's to make fun of the loser.

Oh, man! Did you just see that head shot? Bet you didnt see that coming loser! SI n00b! Better luck next time!

si by Nicholson L. May 17, 2006

Si 

SI : meaning ha ha ha(in a sarcastic tone)or your not very smart
randomly made up on the spot because someone mispelt my name so i said si (because that was the bit they missed out) he said "what?" so i carried on saying si just to make him feel like he'd missed out on something. now it is a word! i hope:)

someone makes a joke about you thats not very funny you say "si si"
OR
someone answers a question wrong you say "si" and laugh

Si by Hannah macintosh April 11, 2004

si 

VERY sweet, cute, attractive, thoughtful, smart, funny young woman found in and around the London area. Keep your eyes peeled but dont touch, she's already claimed ;)

Just think of someone that fits the description above - there's only one person you can think of!

si by shiftkis May 16, 2003

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'

SI by Anonymous June 26, 2003