'blood-vessel-dilating' originates from Modern English, specifically the words 'blood', 'vessel', and 'dilate', where 'blood' referred to the bodily fluid in veins and arteries, 'vessel' meant 'a tube or canal' and 'dilate' meant 'to expand or widen'.

'dilate' originates from Latin 'dilatare' (to spread out, enlarge); it passed into Old French and Middle English forms before becoming the modern English 'dilate'. The compound form 'blood-vessel-dilating' is a descriptive modern combination of existing English words.

Initially, components like 'dilate' meant 'to spread out or expand' in Latin; over time the sense narrowed in medical English to specifically mean 'to widen (a passage or vessel)', which is preserved in the current phrase meaning 'causing blood vessels to widen'.