Thirds rhymes with:
third's, twothirds, bird's, birds, birds', byrd's, gerdes, gerdes', girds, herds, kurds, nerds, n_words, third's, twothirds, word's, words
Thirds sounds like:
tarots, tarts, tertius, tetrads, third's, thirties, thirty's, thordis, thortec, threads, threats, throats, thwarts, tirades, tortoise, tortoises, torts, tortuous, tourette's, touretzky, towards, trade's, trades, traits, treads, treaties, treatise, treatises, treats, treaty's, triad's, triads, tridex, tritch, trites, tritsch, tritz, trots, trotsky, trout's, trudge, trudges, truths, tryouts, turrets, twardowski, twothirds