'later-added' is a compound of 'later' and 'added'. 'later' originates from Old English (comparative of 'late'), and 'added' comes from Latin 'addere' (via Old French), where 'ad-' meant 'to' and 'dere/dare' meant 'to give'.

'later' developed as the comparative form of Old English 'læt'/'lǣt' (meaning 'late' or 'slow'), while 'add' entered English from Latin 'addere' through Old French 'ajouter' into Middle English. The hyphenated compound 'later-added' is a modern English formation used to describe items introduced after an initial version.

Initially it simply described something that was 'added at a later time'; this literal meaning has largely remained stable and is retained in modern usage.