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