Arolsen, a town of Germany, capital of the principality of Waldeck (which according to the convention of 18G7 is now administered by the king of Prussia), on the Aar, 12 m. N. of Wal-deck; pop. in 1867, 2,148. The palace contains many works of art and a library of 80,000 volumes. In the parish church are statues by Ranch, and by Kaulbach, who was born here.