(もん)

もん
noun
mon (old currency unit)
money
1. mon — a unit of currency in pre-modern Japan
A common small unit of currency in Japan from the medieval period through the Edo period, used until the yen replaced it in 1871. A single mon was a trivial sum, so the word often appears in proverbs and set phrases meaning "a tiny amount of money."
一文(いちもん)()っていない
I don't have a single mon. (= I'm penniless.)
Something like that isn't worth even three mon. (= It's worthless.)
Prices in the Edo period were expressed in a unit called the mon.

An old currency unit, replaced by the (えん) (yen) in 1871. It survives mainly in idioms that express "a tiny sum."

Common expressions

Usage

Read ぶん, the same kanji means "sentence; writing"—a separate word. As もん it was also a historical unit for shoe size.