also: いちにちのちょう
slight superiority; a bit more experienced
Used when someone has a small but meaningful edge in knowledge, skill, or experience over others. Often appears in phrases like 一日の長がある.
彼はこの分野で一日の長がある。
He has a slight edge in this field.
The difference in experience showed as a slight superiority.
being slightly older
Rare, literal sense referring to being older by a day or a small amount. Seldom used in modern conversation; the superiority sense is dominant.
彼は私より一日の長があるだけだ。
He is only slightly older than me.