The story
From the Arabic phrase اَلْظَهْرُ اَلْدُبِّ اَلْأَكْبَر (al-ẓahru l-dubbi l-ʔakbar, “the back of the great bear [i.e. Ursa Major]”), from ظَهْر (ẓahr, “back”) + دُبّ (dubb, “bear”) + أَكْبَر (ʔakbar, “great”).
Etymology from Wiktionary, CC BY-SA 4.0.