Mortems rhymes with:
ageratums, argosystems, atoms, autumn's, bantam's, bantams, biosystems, bottom's, bottoms, cablesystems, customs, ecosystems, items, microsystems, microsystems', phantoms, quantum's, subsystems, symptoms, system's, systems, systems', techsystems, totems, ultimatums, ultrasystems, victim's, victims
Mortems sounds like:
maertens, maradona's, maradonna's, marathons, marauding, maritimes, martens, martens's, martians, martin's, martinec, martinek, martines, martinez, martinez's, marting, martinique, martinis, martinka, martinko, martins, martins's, mehrtens, meridian's, meriting, mertens, mertins, morton's