Backpack rhymes with:
aipac, compaq, deepak, dynapac, eastpac, gopac, innopac, killpack, midpac, peapack, rempac, schupak, transpac, waguespack, wespac, westpac
Backpack sounds like:
backpacks, backups, bagpipes, bake-offs, bespeak, bespeaks, biceps, bishop's, bishops, bishops', bookshops, boskovich, bukavu's, bukovsky, busboys