Lastly rhymes with:
astley, ghastly, vastly, astley, costley, costly, dishonestly, earnestly, firstly, ghastly, ghostly, honestly, justly, manifestly, modestly, mostly, priestley, priestly, robustly, steadfastly, unjustly, vastly, westley
Lastly sounds like:
lighthall, lightle, lightly, liljedahl, locatelli