full-day

The compound adjective 'full-day' is a modern formation built from two ancient Germanic roots. 'Full' descends from the Proto-Germanic fullaz, itself from the Proto-Indo-European pl̥h₁nós ("full"), a concept relating to completeness. 'Day' originates from Proto-Germanic dagaz, likely from the PIE root dʰegʷʰ- ("to burn, be hot"), referring to the daylight hours. The logic of the compound is transparently literal: combining "complete" with "day" to create a term specifying an activity or service that occupies the entire standard duration of a day, contrasting with terms like 'half-day.' This formation follows the productive English pattern of creating compound adjectives directly describing temporal scope.

Structure: full (complete) + day (a 24-hour period) - full: From Old English full, meaning "complete, entire." It functions as an adjective modifying the noun 'day' to indicate completeness of extent. - day: From Old English dæg, meaning "day, a 24-hour period." It functions as the core noun specifying the unit of time.