Stupidity rhymes with:
cupidity, cupidity, cupidity, illiquidity, lividity, lucidity, rancidity, conticommodity, cupidity, fecundity, illiquidity, lividity, lucidity, nudity, rancidity
Stupidity sounds like:
seedpod, stabbed, staffed, staved, steeped, stepped, steptoe, stiffed, stooped, stopped, stubbed, stuff-it, stuffed, stupid, sudafed