also: ずいいつ
Used to single out the top example in a category, often in formal or written contexts. Commonly follows a noun with の, e.g., 日本随一の〜.
He is the best pianist in Japan.
この地域は全国随一の米どころとして知られている。
This region is known as the number one rice-producing area in the country.
This hot spring boasts the largest scale in Japan.
He is the most skilled person in this industry.