3 letters:
nat, net, nit, nor, not, nut, wat

4 letters:
gaut, gnat, haut, knit, knot, knut, laut, nall, nate, naus, neat, neet, nett, newt, nite, nohr, noss, note, nott, nutt, snot, taut

5 letters:
gnaws, knaub, knauf, knaup, knaus, knoff, knorr, knott, knous, knute, maute, nault, nauss, night, norte, notte

6 letters:
ayotte, faught, fought, gnawed, haught, knauff, knauss, knight, rought, sought, taught, vaught, vought

7 letters:
naughty, thought, wrought