'word-internal' originates from English, formed by combining 'word' (from Old English 'word') and 'internal' (from Latin 'internus' via Old French/Latin), where 'word' meant 'speech' or 'utterance' and 'internal' meant 'inward' or 'inside'.

'internal' comes from Latin 'internus'; it passed into Middle English via Old French and Middle English forms of 'internal'. The compound 'word-internal' is a modern English technical formation combining native English 'word' with the adjective 'internal'.

Initially, 'internal' meant 'inward' or 'inside'; over time it retained that sense and came to be used in specialized compounds (such as 'word-internal') to mean 'inside a word' in linguistic contexts.