the origin of Osaka

What's the origin of ‘Osaka’?　大阪　means big slope by Kanji. I searched it and it was almost correct answer. Strictly speaking, the origin of osaka be seemed a gentle slope.

A chilly night....Love osaka:) What a Wonderful World - Louis Armstrong http://www.youtube.com/watch?v=vnRqYMTpXHc

I'm thinking about fixed amount benefit. My list of things wanting , a camere and a refrigerator, an airline ticket of Spanish line and more... This happy thinking bother me sometimes. But they are higher cost than fixed amount benefit.