Refers to thick, muddy, often toxic sediment or waste, especially industrial or environmental sludge.
Sludge has built up on the riverbed.
Sludge from the factory flowed into the river.
ヘドロの処理には特別な設備が必要だ。
Special equipment is needed to treat the sludge.
工場は排水口のヘドロを定期的に除去している。
The factory regularly removes sludge from its drainage outlet.
In summer, the sludge in the pond gives off a foul smell.
Standard katakana spelling for this loanword.
Hiragana spelling; less common than katakana but still used.
Loanword from English 'sludge', adapted into Japanese as ヘドロ. The exact phonetic shift from 'sludge' to ヘドロ is uncertain, but it likely entered via early industrial or environmental terminology.