four-hour

The compound adjective 'four-hour' is a modern English formation that transparently combines two ancient elements. The first element, 'four', descends from the Proto-Indo-European root kʷetwóres, which has remained remarkably stable in meaning across millennia into its Germanic and Old English forms. The second element, 'hour', has a more complex journey, originating from the Greek hṓrā, which broadly meant a fixed period or season, before being narrowed to a specific time division in Latin and subsequently borrowed into English via French. The compound's logic is purely descriptive, directly linking a quantity to a temporal unit to specify duration, a common and productive pattern in English for creating adjectival phrases.

Structure: four (number) + hour (unit of time) - four: From Old English fēower, from Proto-Germanic fedwōr, from Proto-Indo-European kʷetwóres. Functions as a numerical quantifier. - hour: From Anglo-French houre, Old French hore, from Latin hōra, from Greek hṓrā (season, time, hour). Functions as a noun denoting a unit of time.