day-long

The compound adjective 'day-long' is a transparent formation from two native English elements. 'Day' originates from the Old English 'dæg', a term of Proto-Germanic origin referring to the period of daylight. 'Long' derives from the Old English 'lang' or 'long', also from Proto-Germanic, meaning 'having great linear extent or duration'. The compounding process is straightforward and modern, combining these two core concepts to create a descriptive term. The logic is purely syntactic, where 'long' modifies 'day' to specify the duration, resulting in the meaning 'lasting as long as a day' or 'throughout the entire day'. This pattern is common in English for creating time-specific duration adjectives, such as 'night-long' or 'week-long'.

Structure: day (the period of light) + long (having great duration) For each part, specify its linguistic origin (e.g., Latin, Greek, Old English) and its functional role in the word.