プログレッシブ和英中辞典(第4版)の解説
いっきゅう【一級】
❶〔第１位の等級〕the top level [rank]
彼女の演技は第一級だ
Her acting is first-class.
❷〔一つの級〕one class [rank]；〔学級〕one grade
一級昇進する
be promoted one grade [rank]
英検一級を取得する
get a Grade-1 ranking on the English Proficiency Test／pass the English Proficiency Test at the Grade-1 level
一級品
the finest [choicest] articles; first-class goods
この生地は一級品です
This material is of the highest quality.