Porpoise rhymes with:
corpus, corpus, all-purpose, bippus, bumpus, campus, chapas, chiapas, compas, compass, coppess, copus, corpus, encompass, eohippus, gyrocompass, hippocampus, hospice, kappus, lapis, lupus, malpass, manglapus, molpus, molpus', mopus, multipurpose, negropalpus, oedipus, olympus, opus, pappas, pompous, prapas, precipice, purpose, tapas
Porpoise sounds like:
paperback, paperbacks, paperboy's, paperboys, paribas, paribas's, perhaps, perovich, perpich, poorbaugh, porpoises, powerbook, powerpc, powerpcs, powerpcs', prapas, prefabs, preface, prefix, prepackage, prepuce, previews, previous, priebke, privacies, privacy, probasco, probe's, probes, proboscis, probus, profess, professes, profs, profuse, proofs, propes, prophecies, prophecy, prophesies, propose, proposes, propps, props, proves, provigo, provigo's, proviso, provisos, provoke, provokes, provus, purpose, purposes, purves, purveys, purvis