Brasil, also known as Hy-Brasil and several other variants, is a phantom island said to lie in the Atlantic Ocean west of Ireland. Irish myths described it as cloaked in mist except for one day every seven years, when it becomes visible but still cannot be reached.

The name Brazil is a shortened form of Terra do Brasil, a reference to the brazilwood tree. The name was given in the early 16th century to the territories leased to the merchant consortium led by Fernão de Loronha, to exploit brazilwood for the production of wood dyes for the European textile industry.