Powerbook rhymes with:
overbook, bankbook, checkbook, cookbook, guidebook, handbook, hornbook, jokebook, logbook, matchbook, notebook, omnibook, overbook, passbook, pocketbook, redbook, rulebook, schoolbook, scrapbook, sketchbook, sourcebook, storybook, subnotebook, textbook, yearbook
Powerbook sounds like:
paperback, paperbacks, paperboy's, paperboys, paribas, paribas's, perhaps, perovich, perpich, poorbaugh, porpoise, porpoises, 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