1)a man who dresses in an abnormal fashion, thinking they are somewhat "cool".
2)A euphamism for a person who is rather average at sport, who in actual fact believes they are rather athletic.
3) a term used to describe a poorly constructed haircut.
1) "man, why would you wear fishnets and soccershorts? are you a nimwah?"
2) "look at that guy run, he doesnt realise he is coming last...what a nimwah"
3) " mate surely you didn't pay for that haircut! that is a deadset nimwah!"