Dorian pert. to Doris, a division of ancient Greece; (mus.) name of one of the ancient Gr. musical modes. XVII. f. L. Dōrius — Gr. Dṓrios, f. Dōrís; see -IAN.
So Doric Dorian XVI; one of the main dialects of ancient Greek; (hence) rustic; one of the Greek orders of architecture XVII. — L. Dōricus — Gr. Dōrikós.

Dorian a member of a Hellenic people speaking the Doric dialect of Greek, thought to have entered Greece from the north c.1100 bc. They settled in the Peloponnese and later colonized Sicily and southern Italy.
Dorian mode the mode represented by the natural diatonic scale D-D (containing a minor 3rd and minor 7th).