Ottawa rhymes with:
chippewa, chihuahua, chippewa, denwa, duchossois, gadbois, livernois, quebecois, quebecoise, arkansas, backsaw, baja, bhiksha, bluelaw, brauhau, chihuahua, chippewa, chutzpah, coleslaw, dada, denwa, duchossois, gadbois, gondwana, grandpa, hoopla, kershaw, livernois, mardi-gras, narasimha, omaha, panama, philyaw, quebecois, quebecoise, rorschach, yamaha, zsa-zsa, zsazsa
Ottawa sounds like:
o'day, o'dea, o'dowd, oad, oat, oath, oathout, oda, oday, odd, oddi, oddity, oddy, ode, odea, oded, odette, odowd, ot, ota, otey, otha, ott, ottaway, otte, otto, out, outdate, outdated, outdid, outdo, outed, outta, outwit, outwitted, owada, owed