Piltdown rhymes with:
meltdown, blastdown, countdown, letdown, meltdown, putdown, shootdown, shutdown, writedown, ashdown, blastdown, breakdown, clampdown, closedown, comedown, countdown, crackdown, drawdown, godown, hillsdown, hoedown, knockdown, lansdowne, letdown, lockdown, lowdown, markdown, meltdown, putdown, rundown, shakedown, shootdown, showdown, shutdown, slowdown, southdown, sundown, touchdown, turndown, underdown, writedown
Piltdown sounds like:
paladin, paladino, palatine, paldon, palladino, palladium, pallidotomy, palton, pelton, platen, platinum, platona, platoon, platten, plowden, plutonian, plutonium, politano, pollution, poppleton, population, poulton