Omnicom rhymes with:
genicom, genicom, millicom, verticom, acecomm, beckom, belgacom, careercom, ficom, francom, genicom, globcom, incom, intelcom, metcom, micom, millicom, neukom, opcom, secom, sodecom, stratacom, syncom, telecom, telekom, verticom, viacom, wascom
Omnicom sounds like:
o'hanesian, ohanesian, omission, oncogen, oncogene, onecomm, onken