first-century

The compound adjective 'first-century' is a modern English formation that combines two elements of ancient lineage to precisely denote a historical period. The term 'first' originates from the Old English 'fyrst', itself a superlative form from a Proto-Germanic root meaning 'fore', establishing its sense of being primary in a sequence. 'Century' entered English via French from the Latin 'centuria', a military and administrative term for a division of one hundred, which is rooted in the Proto-Indo-European 'ḱm̥tóm' (hundred). The logical construction is transparent: it literally means 'of or pertaining to the initial hundred-year period' of a given era, most commonly used to specify the opening century of the Common Era (1–100 AD) in historical and archaeological contexts.

Structure: first (ordinal number) + century (period of 100 years) - first: From Old English fyrst, foremost, earliest; related to the superlative form of the Proto-Germanic root for 'fore'. Functions as an ordinal number specifying position in a sequence. - century: From Latin centuria, meaning 'group of one hundred', derived from centum (hundred). Functions as a noun denoting a period of one hundred years.