MONA, in Ancient Geography, two islands of this name in the sea lying between Britain and Ireland. The one described by Cæsar, as situated in the middle passage between both islands, and stretching out in length from south to north. Called Monaeda (Ptolemy); Monapia, or Monabia (Pliny). Supposed to be the isle of Man.—Another Mona (Tacitus); an island more to the south, and of greater breadth; situated on the coast of the Ordovices, from which it is separated by a narrow strait. The ancient feat of the Druids. Now called Anglesey, the island of the Angles or English.