じゅうねんいちじつ・じゅうねんいちにち

十年一日

表記・読み：じゅうねんいちじつ・じゅうねんいちにち

1. 1

   without intermission for ten (long) years; with constancy of purpose for ten (long) years; in the same old rut for years on end

   名詞yojijukugo