Sardonic rhymes with:
hedonic, allophonic, audiotronic, avionic, blahnik, bubonic, catatonic, chronic, conic, connick, demonic, diasonic, diatonic, electronic, embryonic, fibronic, flextronic, ganglionic, gnomonic, harmonic, hedonic, hegemonic, histrionic, hyaluronic, hydroponic, hypersonic, hypertonic, ionic, ironic, isoelectronic, isotonic, kronick, laconic, lasersonic, leptonic, masonic, medtronic, microelectronic, miltonic, mnemonic, monophonic, napoleonic, neoplatonic, nucleonic, ovonic, panasonic, personic, pharaonic, philharmonic, phonic, photronic, planktonic, plantronic, platonic, plutonic, pneumonic, polyphonic, propionic, respironic, sonic, supersonic, symphonic, synchronic, tectonic, telectronic, telephonic, tonic, tranzonic, tronic, ultrasonic, vanik, varitronic
Sardonic sounds like:
sacredness, sardinas, sardines, scrutinize, scrutinizes, scrutton's, secretions, sheraton's, shirting, shortening, shortens, shorting, shortness, shredding, shrewdness, shrouding, skirting, skywriting, sorting, squirting