Translation guide
A topcoat is an overcoat worn over other clothing for warmth or style. In Japanese, the most common word is コート, but more specific terms exist depending on formality and style.
topcoat (general)
formal overcoat
A warm or stylish coat worn over other clothes, typically in cold weather.
The most common and versatile word for any kind of coat or overcoat. Safe to use in most situations.
It's cold, so put on a coat.
This coat is very warm.
A more formal or literary term for an overcoat. Often used in written language or formal contexts.
A long, formal overcoat often worn with business attire or suits.
A classic, formal overcoat with a velvet collar, often single-breasted.
Refers specifically to the Chesterfield style topcoat. Used mainly in fashion or when describing a particular coat.
His Chesterfield coat gives an elegant impression.
コート is the everyday word for any coat. 外套 is formal/literary and less common in speech. オーバーコート specifically means a formal overcoat, often worn over a suit.
I'm going to buy a coat.
I took off my overcoat and hung it on a hanger.
In English, 'topcoat' can specifically mean an overcoat, but in Japanese, コート covers all types of coats (including jackets). If you need to specify an overcoat, use オーバーコート or describe it as スーツの上に着るコート (a coat worn over a suit).
He wore a topcoat over his suit.
I need a new topcoat for winter.
彼は黒い外套を着ていた。
He was wearing a black overcoat.
A light topcoat is useful in early spring.