Green’s Dictionary of Slang

(US) a polysyllabic or supposedly ‘difficult’ word.

1929		Outlook & Independent 151 226/2: We have striven to [...] always le mot juste, the real fifty- cent word that you can't even find in the cheap desk dictionaries.
1939		W. Winchell On Broadway 20 Jan. [synd. col.] Avidly discussing the ‘meaning’ of the play during intermissions, with a sprinkling of 50 cent words.
1989		D. Waters Heathers [film script] VS: That’s good, but Heather would never use the word ‘myriad’. JD: This is the last thing she’ll ever write – she’ll want to cash in on as many fifty cent words as possible.
1996		E.A. Hamilton Newsletter Design 51: You’ve used so many fifty-cent words. How many Americans know what ‘postprandial’ means? Simplify.
2005		J. Stahl I, Fatty 148: The man was a dictionary of 25-cent jawbreakers.