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, called Monavada (Ptolemy); Monapia, or Monabia (Pliny), is supposed to be the isle of Man.—Another Mona (Tacitus); an island more to the south, separated from the coast of the Ordoices by a narrow strait. The ancient seat of the Druids. Now called Anglesey, the island of the Angles or English.