Protocol rhymes with:
socol, thiodiglycol, velsicol, accival, aerosol, afterall, alcohol, amdahl, atoll, beachball, berchenall, bergdoll, bergenthal, birkedal, colestipol, drywall, ekdahl, felsenthal, girozentrale, goldenthal, grondahl, hydrosol, intercontinentale, kuykendall, lindahl, lundahl, methanol, minimill, omdahl, opdahl, orenthal, paintball, rindahl, rosendahl, sandahl, sheldahl, skerdal, skirdall, socol, sundahl, taxol, thiodiglycol, underdahl, vanderwal, vanderwall, velsicol, weisenthal, westfahl, youngdahl
Protocol sounds like:
paradoxical, paradoxically, particle, periodical, periodically, portugal, portugalia, pretzel, pritzl, prodigal, prodigiously, protigal