Translation guide
The English word 'decay' covers physical rotting, decline of systems or morals, and scientific processes like radioactive decay. Japanese uses different words depending on what is decaying and how.
Describe something organic breaking down naturally, like food, wood, or a body.
The most common word for organic matter rotting or spoiling. Used for food, wood, flesh, etc. Intransitive.
この肉はもう腐っている。
This meat has already decayed.
湿気で床が腐った。
The floor decayed due to moisture.
More formal or technical term for decomposition, often used for food spoilage or political/moral decay.
食品の腐敗を防ぐ。
Prevent food from decaying.
Literary or poetic word for decaying, often used for wood, buildings, or remains. Implies a slow, natural process.
古い家が朽ちていく。
The old house is decaying.
Specifically refer to cavities or dental caries.
The standard word for a cavity or tooth decay. Can be used as a noun or with になる.
虫歯ができた。
I got a cavity (tooth decay).
甘いものは虫歯の原因になる。
Sweets cause tooth decay.
Medical/dental term for caries. Used in professional contexts.
う蝕の治療を受ける。
Receive treatment for dental decay.
Describe a gradual worsening of standards, power, or quality.
General term for decline, withering, or decay of power, culture, industry, etc.
その文明は衰退した。
That civilization decayed.
地域経済の衰退が問題だ。
The decay of the local economy is a problem.
Moral decay, corruption, or depravity. Often used for individuals or society.
彼は酒とギャンブルで堕落した。
He decayed morally through alcohol and gambling.
Decadence, degeneration, often artistic or cultural decay. Can be used as 退廃する or 退廃的.
Scientific term for the process of an unstable atomic nucleus losing energy.
Standard physics term for radioactive decay.
ウランは放射性崩壊する。
Uranium undergoes radioactive decay.
General word for collapse or disintegration, used in physics for decay. Often combined with 放射性.
原子核が崩壊する。
The atomic nucleus decays.
Describe physical deterioration of man-made structures over time.
Aging and deterioration, commonly used for buildings, facilities, or equipment.
橋が老朽化している。
The bridge is decaying (deteriorating from age).
Desolation, ruin, decay of land or buildings, often implying neglect.
廃墟が荒廃している。
The ruins are decaying.
腐る is the everyday word for rotting (food, wood). 朽ちる is literary and implies a slow, natural decay over time, often for wood or remains. 腐敗する is formal and used for decomposition or moral decay.
腐る is specifically for organic matter. For buildings or infrastructure, use 老朽化する or 荒廃する. For abstract decline, use 衰退する.
退廃的な芸術。
Decadent (decaying) art.