Dictionary.net

In music, the oldest of the authentic modes or keys of the Greeks. Its character is severe, tempered with gravity and joy, and is adapted both to religious services and to war. Many of the most characteristic Gaelic airs are written in the Dorian mode. Strictly speaking, music in the Dorian mode is written on a scale having its semi-tones between the second and third and the sixth and seventh notes of the scale, instead of between the third and fourth and seventh and eighth as in what is now called the natural or normal scale. In other words, the second note of the normal scale acquires something of the dignity, force, or position of a tonic, and upon it the melodies of the Dorian mode close.