Unions' rhymes with:
union's, unions, reunions, runions, union's, unions, californian's, californians, canyon's, canyons, companions, dominion's, kenyans, minions, onions, opinions, reunions, runions, union's, unions, virginians
Unions' sounds like:
umansky, umass, unanimous, unease, uneasy, unesco, ung, ungo, unhinge, unhook, unigesco, union's, unionize, unions, unique, unisex, unisys, unisys', unisys's, unix, unmanage, unmask, unos, unwise, unz