The story
From Ge'ez ቆባረ (ḳobarä, “darkness, blackness; fog, mist, dust”), from ቆበረ (ḳobärä, “become black, dark, or foggy”), which Antoine d'Abbadie said derives from the root ق ب ر (q b r, “bury”, root), because it "buries" the landscape and obscures the stars. Wolf Leslau alternatively speculated that it is "perhaps related" to Arabic كفر (kifr, “darkness of the night”) from the root ك ف ر (k f r, “conceal”, root).
Etymology from Wiktionary, CC BY-SA 4.0.