3 letters:
mon, zen, zoe, zon

4 letters:
boan, boen, bohn, bone, bown, coan, cohn, cone, doan, fone, goan, goen, hoen, hone, joan, jone, koen, loan, lone, moan, moen, mone, roan, roen, rone, sewn, sown, tone, xene, zahn, zane, zaun, zhan, zine, zinn, zona, zurn

5 letters:
arone, bohne, bowne, doane, doanh, hoehn, known, koehn, kohne, phone, rhone, roane, shone, shown, thoen, thone, zoned, zones

6 letters:
boehne, hoehne, koehne, schoen, schone