'argyll' originates from Scottish Gaelic, specifically the word 'Earra-Ghàidheal', where 'earra' meant 'coast' and 'Ghàidheal' meant 'Gaels'.

'argyll' changed from Scottish Gaelic 'Earra-Ghàidheal' into Scots/English forms such as 'Argyle'/'Argyll' and eventually became the modern English word 'argyll'.

Initially, it meant 'coastland of the Gaels', but over time it evolved into its current meaning referring to the region in western Scotland (and by extension people or things from that region).