Atrium rhymes with:
yttrium, aquarium, auditorium, bacterium, barium, crematorium, delirium, deuterium, disequilibrium, emporium, equilibrium, herbarium, honorarium, merriam, miriam, moratorium, myriam, mysterium, opprobrium, planetarium, tellurium, thorium, yttrium
Atrium sounds like:
aderman, adorn, adorna, adorno, adrian, adriana, adriano, adrienne, athearn, atorino, attermann, attorney, auditorium, audran