delusion of grandeur

delusion of grandeur (plural delusions of grandeur)

1. (usually in the plural) The false belief that one is important or powerful, accompanying certain mental disorders.
2. (usually in the plural) Conceitedness or overconfidence.
   • 2004, Tom Shone, Blockbuster: How Hollywood Learned to Stop Worrying and Love the Summer, page 285:

     [A]s Han Solo, always the voice of reason in the series, says, “I'm out of it for a little while, and everyone gets delusions of grandeur.”

• megalomania