also: ニッカズボン
noun
Abbreviation of ニッカーボッカー; refers to loose-fitting trousers gathered at the knee, often worn for sports or outdoor activities. Somewhat dated but still used in historical or fashion contexts.
祖父の若い頃は、ゴルフでニッカーズボンを履くのが普通だった。
When my grandfather was young, it was normal to wear knickerbockers for golf.
この写真の男性は、ニッカーズボンにハイソックスという出で立ちだ。
The man in this photo is dressed in knickerbockers and knee-high socks.