delirious vs delirium, What's the Difference?

Which to use

“delirious” is an adjective and “delirium” is a noun - they look or sound alike but fill different roles in a sentence.

#30,757
“delirious” frequency rank: #30,391
“delirium” frequency rank: 61148
confusion score

Side-by-Side Comparison

Feature	delirious	delirium
Definition	Being in the state of delirium.	A temporary mental state with a sudden onset, usually reversible, including symptoms of confusion, inability to concentrate, disorientation, anxiety, and sometimes hallucinations. Causes can include dehydration, drug intoxication, and severe infection.

Where the spellings diverge

Shared letters are muted; the letters that actually set delirious and delirium apart are highlighted. They share 7 letters in sequence, which is exactly why the eye skips the difference.

9 ch

delirious

8 ch

delirium

Spelling & Dictionary Insight

delirious and delirium form a confusable pair in the English index, two distinct headwords that are easily confused because they look alike, sound alike, or both. They differ by 1 letter(s) in length - close enough that the eye skips over the difference, far enough that meaning fully diverges. Our composite confusion score for this pair is 61148, derived from the frequency rank of both members and their visual similarity.

delirious is recorded at frequency rank #30,757, classified as anadj, pronounced /dɪˈlɪə̯.ɹi.əs/. delirium is at rank #30,391, tagged as anoun, pronounced /dɪˈlɪ.ɹi.əm/.

Glosses for this pair are partially populated in our dataset, but the full side-by-side definitions above should still guide you to the right choice.

With a confusion score of 61148, this pair ranks #95,925 of 530,003 scored English confusable pairs - among the most confusable pairs.

Frequency comparison

delirious#30,757

delirium#30,391

Source: FrequencyWords open word-frequency list

Frequently Asked Questions

Can "delirious" and "delirium" be used interchangeably?

No, "delirious" and "delirium" have distinct meanings and cannot be swapped without changing the meaning of a sentence. Understanding the specific definition and context for each word is essential for correct usage.

Remembering delirious vs delirium

The fastest way to pick the right one every time.

Check the role first: if you need an adjective, it's “delirious”; for a noun, it's “delirium”.
See each word in full, definition, IPA, etymology and its other confusables. Full “delirious” entry
Browse more pairs most likely to be confused. Most confusable