noun
Sincerely yours; with apologies for brevity
Formal letter closing phrase used when the writer apologizes for the letter's brevity or informal style. Implies the letter was written hastily or without full formality.
手紙の最後に「草々不一」と書いて結んだ。
I closed the letter with 'Sincerely yours (with apologies for the brevity).'
草々 is a simpler closing meaning 'Sincerely yours' without the explicit apology for brevity. 草々不一 adds the nuance of 'please excuse the rough/informal writing'.
不一 alone means 'not one' or 'incomplete', and in letter closings it implies the letter does not fully express the writer's thoughts. Combined with 草々, it strengthens the apology for brevity.
Composed of 草々 (sōsō, 'sincerely yours' or 'roughly written') and 不一 (fuitsu, 'not one' or 'incomplete'). The phrase literally suggests the letter is hastily written and does not fully convey the writer's feelings.