Tretter rhymes with:
fretter, retter, better, bettor, debtor, detter, etter, fetter, fretter, geter, getter, jetter, ketter, letter, metter, mettur, netter, petr, petre, petter, pipetter, retter, schetter, setter, shetter, stetter, sweater, tschetter, vetere, vetter, wetter, yetter
Tretter sounds like:
tartar, tarter, territory, tertiary, tortora, torture, torturer, trader, traitor, treater, treder, trotter, trottier