Nth rhymes with:
drenth, tenth, absinthe, amaranth, billionth, coelacanth, corinth, cynth, drenth, dushyanth, eighteenth, eleventh, eranthe, fifteenth, fourteenth, helminth, hyacinth, hyacinthe, jacinth, jacinthe, labyrinth, millionth, month, nineteenth, ninth, plinth, rhodanthe, seventeenth, seventh, sixteenth, tenth, thirteenth, threemonth, umpteenth
Nth sounds like:
nad, nada, nadeau, nadia, naidoo, naito, named, nandi, nandita, nando, nanette, nat, nata, nate, nath, nathe, nato, nattie, natty, nauta, ndau, nead, neat, ned, neda, nedd, nedda, neddo, nedeau, need, needed, needy, neet, nematode, nemeth, nenet, net, neth, neto, nett, netta, netted, nettie, netto, netty, newmont, newt, niad, niaid, nida, niday, nied, niemuth, nieto, ninad, ninetieth, ninette, ninety, ninth, nit, nita, nite, nito, nitta, nitto, nitty, nod, noda, nodded, node, noeth, nomad, nominate, nominated, nonentity, nonwhite, not, note, noted, noth, noto, nott, notte, nowaday, noyd, nudd, nude, nudey, nudity, nudo, numed, numidia, nut, nute, nutt, nutty, nydia, nyet