diversion to the black market; illicit outflow
Refers to goods or money being illegally channeled away from official distribution into the black market. Often used in economic or crime-related contexts.
戦時中、配給物資の横流れが問題になった。
During the war, the diversion of rationed goods to the black market became a problem.
横流れした資金の行方を追っている。
They are tracing the whereabouts of the illicitly diverted funds.
Compound of 横 (side, illicit) and 流れ (flow). The exact historical derivation is uncertain, but the word likely emerged in the context of wartime or post-war black market activities.