Words That Rhyme With "Undefinedness" :
2 syllables:
blandness, blindness, blondness, china's, Cnidus, dryness, grainedness, grandness, highness, Idas, kindness, linus, Midas, Minos, minus, nidus, roundness, Sandness, shyness, sinus, slyness, soundness, spinous, strainedness, vinous, wryness
3 syllables:
beyondness, echinus, ingrainedness, Longinus, Mutinus, Plotinus, pulvinus, purblindness, rotundness, Socinus, uncinus, unkindness, unsoundness