Potomac rhymes with:
womac, cammack, carmack, cermak, chermak, commack, cormac, cormack, dimock, hammac, hammack, hammock, inasmuch, intermec, maccormack, mccormac, mccormack, primack, romack, slimak, stellmach, stelmach, stelmack, stimac, stomach, womac, wommack
Potomac sounds like:
padding, pathans, patience, patons, patten's, patting, patton's, petitioning, petitions, pettiness, petting, petunias, photodynamic, photons, pittance, pitting, pitying, pivoting, podiums, podunk, potency, potenza, potions, pouting, ptomaines, pudding, puddings, pudong, put-ons, putdowns, putnam's, putting, puttnam's, python's