also: ニッカズボン
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.
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.