dæg

Dæg is the Old English noun meaning day, the daylight portion of a 24-hour cycle, or, more generally, a calendar day. It is the source of the modern English word day. In Old English, dæg was a masculine noun, and it occurs in many compound words and idioms. The term also formed the basis of the days of the week in Old English, including forms that translate to Moon's day and days named after deities.

The word derives from Proto-Germanic *dagaz, related to Old Norse dagr, Dutch dag, German Tag, and Gothic dags. This lineage traces back to a Proto-Indo-European root associated with the light of day and the daily cycle. In Middle English and Early Modern English, dæg developed into the modern word day through phonetic and orthographic changes.

In modern usage, the Old English form survives mainly in historical and linguistic discussion. The everyday English term day has replaced it for ordinary reference to the 24-hour period, while dæg remains important in studies of the language’s history and in discussions of calendars and timekeeping.