Ennui rhymes with:
grenouille, neue, newey, bluey, booee, buoy, chewy, chop-suey, chopsuey, dewey, dewy, duey, ewy, fouhy, fukui, gooey, grenouille, hewey, hooey, huey, hughie, hughy, huie, kooi, kooy, krawccykiewi, lewey, lewi, lewy, marui, matsui, mccooey, mitsui, montrouis, neue, newey, olokuei, phooey, rattatouille, rewey, sansui, screwy, sekisui, shuey, shui, sooy, sourrouille, suey, sui, toohey, tsui, tuohy, uy
Ennui sounds like:
eamon, ehman, ehmann, ehmen, ein, einon, em, ema, emina, emma, emme, emmi, emmie, emmy, emu, en, ena, enea, enema, enemy, enman, ennea, ennen, eno, eon, euan, ewan, ewen, eyman, eynon