Here's what rhymes with under.
wonder thunder sunder plunder asunder blunder Words that almost rhyme with under
hunter umber number lumber bumper plunger jumper slumber outnumber encumber udder other upper utter ulcer rudder runner shudder gunner usher mother color cover summer suffer butter lover rubber buffer sulphur supper vulgar molar sulfur butler comer cutter gutter shutter hover mutter paler rougher sucker tougher buzzer duller succor tuber bugger muffler putter another culture brother younger hunger rupture flutter lustre muster bunker clutter drummer luster tumbler blubber erasure plumber smother vulture crusher duster juster plover smuggler sputter stutter recover cluster juncture ocular puncture uncover youngster ligature bluster coadjutor adjuster scrubber structure discover sculpture sculptor midsummer abductor premolar embrasure pustular tricolor conductor undercover watercolor agriculture instructor restructure aquaculture chronometer conjuncture rediscover filibuster pentameter acupuncture constructor horticulture counterculture substructure cartographer superstructure infrastructure semiconductor superconductor