Oneness is an experience that transcends the mind. When we experience Oneness, we feel a connection with everything in existence on every level. In other words, we feel ‘at one’ with all things.
Another way to put it is that Oneness is the feeling of fullness, vastness, and completion – it is the experience of embodying our true nature, the Self that exists beyond our limited personalities (also known as our egos).
Other names for Oneness often include Non-Dual Awareness, Unity, Buddha-Nature, Christ-Consciousness, and Enlightenment.