Hardier rhymes with:
cordier, bloodier, buddier, cordier, didier, greedier, handier, muddier, needier, odier, readier, rodier, skandia, speedier, steadier, sturdier, verdier
Hardier sounds like:
harder, hardware, harter, hartter, heartier, herder, hereditary, herter, horter, howerter, huerter