magniloquent (adj.)youdaoicibaDictYouDict
1650s, a back-formation from magniloquence, or else from Latin magniloquentia "lofty style of language," from magniloquus "pompous in talk, vaunting, boastful," from comb. form of magnus "great" (see magnate) + -loquus "speaking," from loqui "to speak" (see locution).
roister (v.)youdaoicibaDictYouDict
"bluster, swagger, be bold, noisy, vaunting, or turbulent," 1580s, from an obsolete noun roister "noisy bully" (1550s, displaced by 19c. by roisterer), from Middle French ruistre "ruffian," from Old French ruiste "boorish, gross, uncouth," from Latin rusticus (see rustic (adj.)). Related: Roistered; roistering. Ralph Royster-Doyster is the title and lead character of what is sometimes called the first English comedy (Udall, 1555).
vaunt (v.)youdaoicibaDictYouDict
early 15c., "speak vainly or proudly," from Anglo-French vaunter, Old French vanter "to praise, speak highly of," from Medieval Latin vanitare "to boast," frequentative of Latin vanare "to utter empty words," from vanus "idle, empty" (see vain). Also short for avaunten "to boast" (see vaunt (n.)). Related: Vaunted; vaunting.