Ballast rhymes with:
calloused, agriculturalist, analyst, beautifullest, calloused, capitalist, catalyst, cellist, conversationalist, coolest, cruelest, dullest, evangelist, formalist, fullest, gentlest, gollust, herbalist, humblest, institutionalist, journalist, littlest, monopolist, nationalist, naturalist, neutralist, novelist, palest, panelist, photojournalist, populist, psychoanalyst, simplest, smallest, socialist, specialist, stablest, televangelist, ultranationalist, violist
Ballast sounds like:
balked, belched, bellsouth, belsito, bilked, biologist, blacked, blackest, blackett, blackheath, blackout, blackwood, blast, blasted, blazed, bleached, bleakest, blessed, blest, blight, blighted, blissett, blixt, blockade, blockaded, blocked, blockhead, blowiest, bluest, blushed, blust, bolstad, bulged, bulkhead, bullshit