Trimester rhymes with:
mester, mestre, semester, amvestor, bester, brester, chester, ester, esther, fester, hester, investor, ivester, jester, kester, leicester, lester, mclester, mester, mestre, molester, nester, nestor, pester, polyester, questar, requester, rester, semester, sequester, silvester, sylvester, sylvestre, tester, testor, trester, vestar, vester, westar, wester
Trimester sounds like:
transistor, transitory, transtar