The Chinese character '匁' (monme) is said to have originated from the cursive style writing as '泉,' a homonymy of 銭, or from the Chinese character '文' (mon) attached 'メ' (me), a character of katakana (the square form of kana [Japanese syllabaries]).
「匁」という文字は銭と同音の「泉」の草書体、あるいは「文メ」を続けて書いたものに由来するとされている。