腐る

• Reading: くさる
• Romaji: kusaru
• Kanji breakdown: 腐 (fu/kusa) — rot, decay, spoil
• Pronunciation: /kɯ.sa.ɾɯ/

Meaning

To rot; to go bad; to spoil. Decomposition of food or materials.

A Group 1 (godan) intransitive verb conjugated with the る row. Primarily used for food spoiling (肉が腐る, meat goes bad) but also figuratively for moral corruption (根性が腐っている, rotten attitude) or becoming dejected (腐ってもたい, even rotten, still valuable — from 腐っても鯛). The causative 腐らせる means to let something rot.

Examples

1. 冷蔵庫に入れないと夏はすぐに食べ物が腐る。 If you don't put it in the fridge, food goes bad quickly in the summer.
2. この牛乳は腐っているから飲まないで。 This milk has gone bad, so don't drink it.
3. 雨で木の柱が腐ってしまった。 The wooden pillar rotted because of the rain.

Usage Guide

Context: food, daily life, figurative speech

Tone: negative

Origin & History

From Old Japanese. The kanji 腐 combines 府 (storehouse) and 肉 (meat), depicting meat left in storage until it decomposes — a vivid image of spoilage.

Cultural Context

Era: Ancient

Generation: All ages

Social background: Universal