From the Latin omni - 'all' and benevolent - 'good', literally "all good".

In the Philosophy of Religion, those defending Theism define ‘god’ as a being with three fundamental characteristics: perfect knowledge, perfect power, and perfect goodness.

The perfect goodness or moral reliability of God is a logical corollary of the conjunction of omnipotence and omnisience. If God had the ability to do anything that is doable, and has perfect knowledge (which includes understanding the outcome of any action undertaken), then every act of God will be perfectly reliable.