'armillaria' originates from Latin, specifically the word 'armilla' (bracelet), where 'armilla' meant 'bracelet' or 'armlet'.

'armillaria' was taken into New Latin (botanical/mycological Latin) as the genus name 'Armillaria' because some species have ring-like (bracelet-like) structures on their stems; the modern scientific name thus derives directly from Latin 'armilla'.

Initially, the Latin root meant 'bracelet' (a piece of jewelry), but over time it became the name of a genus of fungi (named for ring-like features) and now refers to those mushrooms and related species.