Definitions
1.NounAn adamant belief in a falsehood despite incontestable evidence.
2.NounThe state of being deluded or misled, or process of deluding somebody."It is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring."
3.NounThat which is falsely or delusively believed or propagated; false belief; error in belief.
4.NounA fixed, false belief, that will not change, despite evidence to the contrary.