Someone who lacks judgement.
Is blinded by some sort of factor, usually emotional.
In the Great Gatsby, Jay Gatsby was a deluded fool.
Nicole: Geee Alexia, your such a stalker, like lay off. He does not like you.
Michelle: I agree, that boy dun like you.
Alexia: But I've been stalking him for 5 years now, I cant let go just like that.
Michelle: your such a deluded fool.