Authentically rhymes with:
acoustically, aesthetically, alphabetically, analytically, apologetically, artistically, athletically, automatically, characteristically, cosmetically, democratically, diplomatically, dogmatically, domestically, dramatically, drastically, ecstatically, emphatically, energetically, enthusiastically, erratically, esthetically, euphemistically, fantastically, genetically, geopolitically, hypothetically, idiotically, linguistically, logistically, optically, phonetically, poetically, realistically, sarcastically, stylistically, synthetically, systematically, thematically, uncharacteristically, undiplomatically, unrealistically, vertically