Theory rhymes with:
thiery, thiry, alfieri, altieri, amiri, arcieri, argentieri, balestrieri, barbieri, barriere, beary, beery, bessire, bieri, biery, bleary, buccieri, caligiuri, caliri, camire, carpentieri, carriere, cavaliere, cavalieri, cheery, cleary, deary, deery, dehere, diery, dreary, eary, eerie, erie, facemire, gearey, geary, granieri, gualtieri, guarnieri, guerrieri, hara-kiri, hariri, intrieri, irimajiri, jiri, keary, kiri, laverdiere, leary, leery, lettieri, mangieri, martire, mccleary, mccleery, mccreary, mccreery, mcgeary, mcleary, mcneary, mcqueary, neary, o'leary, oleary, olivieri, pirie, ruggieri, siri, sirri, sneary, spizzirri, squitieri, staffieri, taglieri, teary, thiery, thiry, weary, wiry, yeary
Theory sounds like:
taher, taira, tar, tara, taro, tarr, tarry, tatar, tater, tatra, tatro, tatter, tauer, tawdry, tear, teare, teary, teater, teatro, tedder, tedrow, teer, teeter, teodoro, ter, terhaar, teri, terra, terre, terri, terrie, terrier, terrio, terror, terry, teruya, teter, tether, tetra, tetro, thar, thayer, theater, theatre, their, theodor, theodora, theodore, theodorou, theora, thera, there, there're, theurer, they're, thier, thierry, thiery, thiry, thor, thora, thoreau, thoro, three, threw, throw, throwaway, thrower, thru, thruway, thur, thurow, thyra, tiara, tidewater, tier, tire, tirey, titter, todaro, tor, torah, toray, tore, torey, tori, torie, toro, torr, torray, torre, torrey, torry, toru, tory, totaro, totherow, totter, tour, touro, tower, towery, towry, traer, tray, trayer, tre, tree, treu, trew, trey, tri, trie, trier, trieu, trio, troha, troia, trow, trower, troy, troyer, troyu, true, truer, truro, try, tudor, ture, turi, turo, turow, turri, tutor, tutterow, tyer, tyra, tyre, tyree