Calmest rhymes with:
promised, alarmist, anatomist, animist, biochemist, dumbest, firmest, gamest, grimaced, grimmest, pessimist, premised, promised, slimmest, taxidermist, warmest
Calmest sounds like:
challenged, cleanest, cleansed, clenched, climaxed, clinched, collingwood, colonist, colonized, columnist