'same-named' originates from Modern English, specifically the combination of the adjective 'same' (from Old English 'sam' meaning 'the same') and the past participle 'named' formed from the verb 'name' (Old English 'nama').

'same-named' developed as a compound adjective in Modern English by joining 'same' + 'named' (the past participle of 'name'), and over time the hyphenated form 'same-named' became a conventional way to describe things that share an identical name.

Initially it was just a literal combination of 'same' + 'named', but it evolved into the established adjectival phrase meaning 'having the same name' used attributively.