Knockdown rhymes with:
lockdown, breakdown, crackdown, lockdown, markdown, shakedown, ashdown, blastdown, breakdown, clampdown, closedown, comedown, countdown, crackdown, drawdown, godown, hillsdown, hoedown, lansdowne, letdown, lockdown, lowdown, markdown, meltdown, piltdown, putdown, rundown, shakedown, shootdown, showdown, shutdown, slowdown, southdown, sundown, touchdown, turndown, underdown, writedown
Knockdown sounds like:
keniston, kennington, kingdom, kingdon, kingston, kington, kinston, knighten, knighton