Wiktionary
finif
n. (context US slang dated English) A five-dollar bill (gloss: note).
Usage examples of "finif".
He did all right, as he should have with the finif I gave him in his pocket, and with that avenue as nearly open as it ever gets.
I removed my gloves, got out my case and extracted a card, got out my wallet and extracted a finif, and said, "On the level.
Here's a finif if its effect will be to keep your trap entirely closed regarding the fun we're having.