(さんもん)

さんもん
noun
three mon (old coin); a pittance; cheap
culture
1. three mon (old copper coin unit); a pittance; trifling amount
Literally 'three mon' — three units of an old copper coin worth almost nothing. Now used figuratively in idioms to mean 'a trifle', 'a cheap thing', or 'a small but real benefit'.
早起(はやお)三文(さんもん)(とく)
The early bird catches the worm. (lit. 'rising early is worth three mon')
そんな三文(さんもん)小説(しょうせつ)すぎない。
That's nothing more than a cheap pulp novel.
Even though he was called a third-rate actor, he kept performing on stage every day.

(もん) was a unit of old Japanese copper coinage; three of them was a very small sum. In modern Japanese the word survives almost exclusively in fixed phrases meaning 'cheap' or 'trifling'.

Common expressions

Usage

Rarely used as a literal price in modern Japanese — almost always appears as part of an idiom or set expression with a 'cheap, worthless, or trivial' nuance.