* asunder, blunder, plunder, refunder, sunder, thunder, under

If you can make a NEAR rhyme work (where most of the sounds match and, preferably, the rest are close). I’ll list those that have the best chance of working.

Fairly close near rhymes (note that /m/ and/n/ are VERY close sounds):

* clumber, (en)cumber, lumber, number, slumber, umber

* hunger, younger

(Incidentally, “cucumber” is NOT likely to work, because its ACCENT falls on a different syllable — CU-cumber vs. UN-der, etc.)

A bit more distant (where the sound after the /n/ or /m/ does NOT use the voice:

* hunter, grunter, punter

* bunker, clunker, debunker, drunker, dunker, flunker, funker, hunker, junker, lunker, plunker, punker, spelunker

* bumper, dumper, gazumper, jumper, lumper, mumper, plumper, pumper, stumper, thumper

Perhaps these (with NO consonant sound after the /n/ or /m/)

* dunner, funner, gunner, punner, runner, stunner

* clummer, crumber, dumber, drummer, hummer, rummer, scummer, slummer, summer, thrummer

OR even these (with the /d/ or the very close /t/, but no /n/…)

* budder, mudder, rudder, shudder udder

* butter, clutter, cutter, flutter, gutter, mutter, nutter, putter, sputter, strutter, stutter, utter

RE:
What rhymes with wonder?

hope-cope, mope,elope, rope, scope slope, pope, tope( meanding of tope verb:to drink liquor in excess, noun:a small slender cosmopolitan shark) wonder-blonder, fonder, bonder(noun), ponder, yonder, thunder, hopes this helps

dunder

plunder

blunder

asunder

under

wonder

asunder

rotunda

under

chunda

.