there are two different definitions, but the word is spelt the same way each time. all depends on the situation and how you are using the word
1. Noshish means NO SHIT
2. or theres Noshish meaning Know shit
1. like if someone said something obvious
"Noshish dude really"
2.Like if someone is being Ignorant
"Shut up Bitch you dont Noshish"
(in that case the word no, means know)