Hardening rhymes with:
gardening, pardoning, gardening, pardoning, abandoning, broadening, burdening, clendening, deadening, gardening, glendening, maddening, pardoning, saddening, widening
Hardening sounds like:
harden's, hardens, harding, harding's, hardness, harting, hartness, hartong, hartung, heartening, herding, herting, hoarding, hurting