The Grammarphobia Blog

Delusions of grandeur

Q: “Deluded” or “delusional”? Do you prefer one over the other? “Deluded” is a syllable and several letters shorter (that’s a plus), but it doesn’t always mean the same thing as “delusional.” Or does it?

A: No, “deluded” and “delusional” don’t mean the same thing, though they share the same Latin root.

The participial adjective “deluded” means tricked or deceived.

The adjective “delusional” means believing things in spite of indisputable evidence to the contrary.

Although “delusional” is often used loosely, it can also mean suffering from delusions, a symptom of mental illness.

“Deluded” and “delusional,” as well as the verb “delude” and the noun “delusion,” are derived from the Latin deludere (to play false, mock, deceive), the Oxford English Dictionary says.

Both “delude” (to mislead) and “delusion” (a false belief) entered English in the 15th century, according to published references in the OED.

The earliest appearances of “deluded” (in the 15th century) were as the past tense and past participle of the verb “delude.”

The participial adjective “deluded” didn’t appear until the 17th century. The first OED citation for the adjective is from a poem (circa 1628) by Sir John Beaumont:

“To taste of heauenly lights your thoughts inclines / And able to wean deluded mindes.” (We’ve gone to the original to expand the citation.) 

The adjective “delusional” is the newcomer here. It didn’t show up until the late 19th century.

The earliest OED citation (a reference to “delusional insanity”) comes from A System of Medicine (1880) by John Russell Reynolds.

By the way, the expression “delusions of grandeur,” which entered English in the early 20th century, refers to a false belief that you’re a bigger shot than you really are.

However, you don’t have to think you’re Napoleon—or even be a human being—to have delusions of grandeur.

In Edna St. Vincent Millay’s Conversation at Midnight, a 1937 play in blank verse, a refrigerator has “Delusions of grandeur, that’s what it’s got, all right; / Thinks it’s the Queen Mary.”

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