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1.
the biggest compliment someone can be given. Few ppl are truly niss, however when someone is, everyone around them knows it and knows that he/she is the don. They must acknowledge his nissness.

Also used to describe things that are unordinarily great.

nissify nissification nissipline
Be niss or be gone!

- ey did u cop the green?
- yea..
- how does it look?
- fucking niss son
by griff August 13, 2006
 
2.
A kiss on the neck. It is like making out with someone's neck region, but not touching their lips.
"Mark didn't kiss me last night, but he gave me a little niss."
by ilikecandy123 June 14, 2009
 
3.
Nice. (Strictly nice)
"Hey, do you like my new ipod?"
"Ahh... niss, niss!"
by tea fish October 25, 2006
 
4.
Niss: an adjetive for words that end in niss,. like retardtedniss, stupidniss, drunkinniss, jackassniss, gayniss, ext.
Mike and Joe always be talking about niss.
 
5.
Niss is everything. Instead of saying "She's tangled up in a bunch of yarn!" you could say, "She's tangled up in a bunch of Niss!" Usually it is used in place of a noun that you can't think of, or you can't explain. May also use nissyfoofoo as a plural form, just for a special thing, or as an exclamation.
That Niss is on fire!
Nissyfoofoo!
by Kastie October 21, 2006