Onions rhymes with:
californian's, californians, canyon's, canyons, companions, dominion's, kenyans, minions, opinions, reunions, runions, union's, unions, unions', virginians
Onions sounds like:
oehmens, ohioans, ohm's, ohms, ohnemus, omaha's, omans, omega, omens, ominous, onassis, onassis', onassis's, once, one's, oneness, oneok, ones, ones', onex, onex's, ong, onishi, ons, onus, onyx, ounce, ounces, owen's, owens, owens's, owing, owings, owning, owns