'thin-snouted' originates from Modern English, specifically the compound of 'thin' + 'snout' with the adjectival suffix '-ed', where 'thin' meant 'not thick; slender' and 'snout' meant 'a projecting nose or beak-like mouthpart'.

'snout' was used in Middle English (also spelled 'snoute') and derives from older Germanic sources; 'thin' comes from Old English 'þynne'. The compound 'thin-snouted' is a straightforward Modern English formation combining these elements.

Initially it literally combined the senses 'thin' + 'snout'; over time the compound has kept the clear meaning 'having a thin snout' without major semantic change.