Definition of ontological argument in US English:
 ontological argument
nounˌän(t)əˌläjəkəl ˈärɡyəmənt
Philosophy The argument that God, being defined as most great or perfect, must exist, since a God who exists is greater than a God who does not.
Compare with argument from design, cosmological argument, and teleological argument
 Example sentencesExamples
-  The most important of those proofs were the ontological argument, the cosmological argument, and the teleological argument.
 -  A third argument - now dubbed the ontological argument - maintains that the greatest possible being must exist since it is logically contradictory to assert otherwise.
 -  So, in the end, all three arguments reduce to the ontological argument, which tells us that God must exist, since existence belongs to the very concept of God.
 -  However, the contention that the cosmological argument depends on the ontological argument is based on a confusion.
 -  Does anybody else know of any other ontological arguments?