Translation guide
The English word "rust" can refer to the reddish-brown coating on iron, the plant disease, or the color. This guide focuses on the most common meaning: the corrosion of iron. Japanese has several words for rust, with 錆 (さび) being the most general and common.
To refer to the reddish-brown flaky coating that forms on iron or steel when it oxidizes.
The most common and general word for rust. Can be used for rust on any metal object, but primarily iron/steel.
自転車のチェーンが錆びている。
The bicycle chain is rusty.
このナイフは錆に強い。
This knife is resistant to rust.
Literally 'red rust', refers specifically to the common red rust (iron(III) oxide). Often used in technical contexts or to distinguish from other types of rust.
赤錆は鉄の表面にできる。
Red rust forms on the surface of iron.
Literally 'black rust', refers to black iron oxide (magnetite) that can form a protective layer. Used in technical or craft contexts (e.g., knife making).
黒錆は鉄を保護する。
Black rust protects the iron.
To refer to a group of fungal diseases that cause rust-colored spots on plant leaves and stems.
The standard term for rust disease in plants. Used in gardening and agriculture.
このバラはさび病にかかっている。
This rose has rust disease.
An alternative kanji for rust disease, but さび病 is much more common. Rarely used.
銹病は穀物に被害を与える。
Rust disease damages crops.
To describe the color resembling rust, a reddish-brown or orange-brown.
Literally 'rust color'. A common way to describe the color in everyday speech.
彼女は錆色のセーターを着ていた。
She was wearing a rust-colored sweater.
Literally 'rusted color'. Slightly more descriptive, often used for objects that look like they have rusted.
壁がさびた色に塗られていた。
The wall was painted a rusted color.
To express the process of metal becoming rusty.
Intransitive verb: to rust, to become rusty. Used when the subject itself rusts.
鉄は水に濡れると錆びる。
Iron rusts when it gets wet.
この自転車はもう錆びてしまった。
This bicycle has already rusted.
Transitive verb: to cause to rust, to let rust. Used when someone/something causes rusting.
湿気が鉄を錆びさせる。
Humidity causes iron to rust.
Literally 'rust attaches'. A common phrase meaning to get rusty. Often used for tools or skills.
使わないと包丁に錆がつく。
If you don't use it, the kitchen knife will get rusty.
To express that a skill or ability has declined due to lack of practice, similar to 'getting rusty' in English.
Literally 'one's arm becomes dull'. A common idiom meaning one's skills have become rusty. Not directly using the word 'rust', but the natural equivalent.
しばらく練習してなかったから、腕が鈍った。
I haven't practiced for a while, so my skills have gotten rusty.
Literally 'one's intuition becomes dull'. Used when one's sense or instinct for something has become rusty.
長い休みの後で、仕事の勘が鈍った。
After a long break, my work instincts got rusty.
Literally 'to become rusty'. Can be used figuratively for skills, but less common than 鈍る. Sounds more literal/metaphorical.
While 錆 can technically refer to corrosion on other metals, it is most strongly associated with iron. For aluminum or copper, you might use 腐食 (ふしょく, corrosion) or specific terms like 緑青 (ろくしょう, verdigris on copper). In casual speech, 錆 is often understood for any metal, but be aware of the nuance.
錆びる is the everyday word for rusting (iron oxidation). 腐食する is a more technical term for corrosion in general, including chemical corrosion of various materials. Use 錆びる for common rust, 腐食する for scientific/engineering contexts.
My English has gotten rusty.