Short answer: A C-note is slang for a $100 bill, derived from the Roman numeral C which denotes 100, and it traces back to when some $100 notes bore the letter C, helping people identify the denomination. Details

• Origin of the term:
  • The letter C is the Roman numeral for 100, so “C” came to symbolize the $100 denomination.

* Historically, early $100 notes sometimes featured a capital “C” on the front, which likely sparked or reinforced the usage of “C-note” as a name for the bill.

* The term gained popular usage in the 1920s–1930s and has since become a recognized slang term in American English, though “Benjamin” or simply “hundred-dollar bill” are also common today.

• Common alternatives and usage:
  • In modern slang, people may say “a Benjamin” (referring to Benjamin Franklin appearing on the note) or simply “a hundred,” but “C-note” remains an understood term, especially in historical or colloquial contexts.

If you’d like, I can share a brief timeline of the $100 bill’s design changes and when the “C” appeared on the currency, or compare regional usage of terms like C-note, Benjamin, and hundred-dollar bill.