The first definition that I would like to provide is the definition of this word that appears all over the website. What is isness? The root of the word is IS. Is means has being. Ness is a suffix that means a state or condition or quality. Isness therefore means something that is and has the quality or condition of being. God is because He IS. Everything else that is, is because God is. The second definition is as follows: God's oneness like His isness is not comparable to anything. Like we mentioned in definition number one that God is because He is, so is His oneness one because He is one. This thought is actually quite uncomprehendable. Our teachers tell us that His onesness is not countable like that which can be numbered. "Hear Yisroel Hashem our God Hasem is ONE" it is from here that the Torah teaches us God's oneness.