noun
underground world; underworld
Refers to the hidden, often illegal side of society: organized crime, black markets, and shadowy networks.
彼は闇社会とのつながりを疑われている。
He is suspected of having ties to the underworld.
その事件は闇社会の存在を浮き彫りにした。
The incident highlighted the existence of an underground society.
Compound of 闇 (yami, 'darkness') and 社会 (shakai, 'society'). The exact origin is uncertain, but it likely emerged as a metaphorical term for the hidden criminal world.