Definition of God
A 'definition of God' is fairly hard to come by; in the major Abrahamic and Vedic faiths, God (in Judaism, Christianity, and Islam), Brahman (in Hinduism) and Buddha Nature (in Buddhism) is often described as the infinite, ultimately unknowable reality outside of space and time that brought forth the universe. In science this is known as the Universal Force. Thomas Aquinas developed the idea of the Via Negativa to deal with this; he argued that instead of finding adjectives to describe God (e.g. 'God is X'), it is more profitable to find words which God is not - 'God is not limited', 'God is not evil', etc.
Nicholas of Cusa said in the 15th Century: "God is like an infinite sphere, whose center is everywhere and circumference nowhere."
This definition is also found in other religions, and is often considered to be part of the Perennial Philosophy.
"The soul is a circle of which the circumference is in a body. God is a circle whose circumference is nowhere but whose center is everywhere." SwamiVivekananda, 19th C.