The Collaborative International Dictionary of English v.0.48:
Oneness \One"ness\, n. The state of being one; singleness in number; individuality; unity. [1913 Webster] Our God is one, or rather very oneness. --Hooker. [1913 Webster]WordNet (r) 3.0 (2006):
oneness n 1: the quality of being united into one [syn: oneness, unity]