Naches- Naches. Also pride.
Nebuchs – losers, pity cases
Neshama - soul
Nefesh, Nefesh Elokis, Nefesh HaBahamis - soul, and the parts of the soul. Nefesh elokis is the G-dly part of the soul, nefesh HaBahamis is the "animal" part of the soul. See Kabbalah or chassidus for more information.
Niggun – A wordless Chassidic song
Nusach Sfard- the liturgy chosen by the Chassidim, in opposition to the traditional liturgy usually used by European Jews, Nusach Ashkenaz