Shiva Purana
दुर्गमाख्यो महादैत्यो हतो यस्मात्ततः शिवे ॥ दुर्गां भगवतीं भद्रां व्याहरिष्यंति मानवाः ॥ ३६ ॥
O Śivā, since you killed the Daitya Durgama you will be known as Durgā.
english translation
durgamAkhyo mahAdaityo hato yasmAttataH zive ॥ durgAM bhagavatIM bhadrAM vyAhariSyaMti mAnavAH ॥ 36 ॥
hk transliteration by Sanscript