Firstar rhymes with:
acustar, aerostar, amstar, apstar, canstar, cellstar, constar, crestar, earthstar, eurostar, flagstar, genstar, globalstar, goldstar, incstar, lodestar, minstar, morningstar, navistar, navstar, norstar, northstar, oberstar, primestar, sunstar, telstar, texstar, torstar, tristar, windstar, wordstar
Firstar sounds like:
fabricator, firstier, foerster, forecaster, forester, forestry, forister, forrester, forster, fracture, freighter, freshwater, fruchter