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  • ill
    ill
    adjective
    of unsound physical or mental health; unwell; sick.
  • I'll
    I'll
    contraction of I will.
  • ill.
    ill.
    abbreviation
    illustrated.
  • Ill.
    Ill.
    abbreviation
    Illinois.
Synonyms

ill

1 American  
[il] / ɪl /

adjective

worse, worst, iller, illest
  1. of unsound physical or mental health; unwell; sick.

    She felt ill, so her teacher sent her to the nurse.

    Synonyms:
    afflicted, diseased, ailing, unhealthy
    Antonyms:
    healthy, well
  2. objectionable; unsatisfactory; poor; faulty.

    ill manners.

  3. hostile; unkindly.

    ill feeling.

  4. evil; wicked; bad.

    of ill repute.

    Synonyms:
    iniquitous, wrong
    Antonyms:
    good
  5. unfavorable; adverse.

    ill fortune.

  6. of inferior worth or ability; unskillful; inexpert.

    an ill example of scholarship.

  7. Slang. great; amazing.

    His mom is the illest cook.


noun

ills plural
  1. an unfavorable opinion or statement.

    I can speak no ill of her.

  2. harm or injury.

    His remarks did much ill.

    Synonyms:
    misery, affliction, pain, hurt
  3. trouble, distress, or misfortune.

    Many ills befell him.

    Synonyms:
    calamity
  4. evil.

    to know the difference between good and ill.

    Synonyms:
    depravity
  5. sickness or disease.

    Synonyms:
    affliction, illness

adverb

  1. in an ill manner.

  2. unsatisfactorily; poorly.

    It ill befits a man to betray old friends.

  3. in a hostile or unfriendly manner.

  4. unfavorably; unfortunately.

  5. with displeasure or offense.

  6. faultily; improperly.

  7. with difficulty or inconvenience; scarcely.

    Buying a new car is an expense we can ill afford.

idioms

  1. ill at ease, socially uncomfortable; nervous.

    They were ill at ease because they didn't speak the language.

I'll 2 American  
[ahyl] / aɪl /
  1. contraction of I will.


ill. 3 American  

abbreviation

  1. illustrated.

  2. illustration.

  3. illustrator.

  4. most illustrious.


Ill. 4 American  

abbreviation

  1. Illinois.


ill 1 British  
/ ɪl /

adjective

  1. (usually postpositive) not in good health; sick

  2. characterized by or intending evil, harm, etc; hostile

    ill deeds

  3. causing or resulting in pain, harm, adversity, etc

    ill effects

  4. ascribing or imputing evil to something referred to

    ill repute

  5. promising an unfavourable outcome; unpropitious

    an ill omen

  6. harsh; lacking kindness

    ill will

  7. not up to an acceptable standard; faulty

    ill manners

  8. unable to relax; uncomfortable

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

noun

  1. evil or harm

    to wish a person ill

  2. a mild disease

  3. misfortune; trouble

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

adverb

  1. badly

    the title ill befits him

  2. with difficulty; hardly

    he can ill afford the money

  3. not rightly

    she ill deserves such good fortune

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Ill. 2 British  

abbreviation

  1. Illinois

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

I'll 3 British  
/ aɪl /

contraction

  1. I will or I shall

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

ill More Idioms  

    More idioms and phrases containing ill


Grammar

See well 1.

Usage

What are other ways to say ill? The adjective ill is defined as “evil; wicked; bad.” However, it’s not used in exactly the same way as any of those synonyms! Learn the difference among these terms on Thesaurus.com.

Synonym Usage

Ill, sick mean being in bad health, not being well. Ill is the more formal word. In the U. S. the two words are used practically interchangeably except that sick is always used when the word modifies the following noun: He looks sick ( ill ); a sick person. In England, sick is not interchangeable with ill, but usually has the connotation of nauseous: She got sick and threw up. sick, however, is used before nouns just as in the U. S.: a sick man.

Other Word Forms

Noun Inflected Forms

Etymology

Origin of ill1

1150–1200; Middle English ill ( e ) (noun and adj.) < Old Norse illr (adj.) ill, bad

Origin of ill.3

ill. ( def. 4 ) < Latin illustrissimus

Explanation

If you're ill, you're unwell, or sick. Being ill is a good excuse for missing work or school. You might get ill after being sneezed on by someone with a cold; or eating street food in a foreign country; or for no reason that you can point to. People can be mentally ill as well as physically ill, from depression or anxiety among other ailments. Ill can also mean "bad" in various ways, including when you suffer ill effects from going too long without sleep, or exercise ill judgment when you buy $500 worth of lottery tickets.

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

In early 1999, Lieberson put her career on hold to nurse her sister Alexis, who was gravely ill from breast cancer.

From The Wall Street Journal Jul. 28, 2026

The dose was low enough that the mothers did not become significantly ill.

From Science Daily Jul. 25, 2026

The delay could make it more difficult for ill people to remember all the foods they ate, “down to a single ingredient in a salad,” before they were stricken, Rimoin said.

From Los Angeles Times Jul. 24, 2026

It comes just a few days after Yates fell ill and vomited after stage 16's time trial.

From BBC Jul. 24, 2026

In 2010, 8.8 million people fell ill with TB, with 1.4 million deaths.

From "Mountains Beyond Mountains" by Tracy Kidder and Michael French

“I was a No. 10, what excites me is scoring goals…I was a leader on the pitch, and I’ll be a leader through what I’ve achieved.”

From The Wall Street Journal Jul. 28, 2026

I’ll return it to another Little Free Library when I’m finished.

From Salon Jul. 28, 2026

"My family and I are never going to heal from this trauma. I'll never be myself again and that's because of Robert Bush."

From BBC Jul. 28, 2026

Starting Aug. 4, I’ll be in your inbox every Tuesday as I officially take the reins as Don’t Short Yourself’s regular writer.

From MarketWatch Jul. 28, 2026

It’s been hard for me to accept that I’ll never again get to work alongside him, crafting another canoe, or tackling his mounds of paperwork.

From "Red Flags and Butterflies" by Sheryl Azzam

"He was critically ill. His heart stopped as soon as he arrived. We had to perform CPR," said lead author Ankit Bharat, a thoracic surgeon at Northwestern University.

From Science Daily Mar. 18, 2026

"I was violently ill. I was sweating. I was cold. I was shaking. I was vomiting for about four or five days."

From BBC Jan. 5, 2026

"All of these people have had hepatitis C for more than three decades; some are very ill. A more proactive approach is critical to reaching and diagnosing those who remain unaware of their infection."

From BBC May 18, 2025

“I was genuinely surprised to see how many of you wrote letters to the judges, telling him I was mentally ill. Like my mother,” she said.

From Salon Oct. 27, 2024

Instead her stepmother turned the key in the lock and woke her, saying, “Beatrice is ill. She won’t be here today.”

From "Ash" by Malinda Lo

Calamos Investments is based in Naperville, Ill., and manages about $52 billion in assets through various strategies.

From MarketWatch Jul. 27, 2026

Ben Zwief, an adviser in Lake Forest, Ill., cites the example of a client with $50,000 in credit-card debt at a 20% interest rate.

From MarketWatch Jul. 2, 2026

The first R2s to roll off the company’s production line in Normal, Ill., are the performance version, starting at $57,990.

From Los Angeles Times Jun. 10, 2026

Gleeson, of St. Joseph, Ill., set out to buy a new car six years ago, but couldn’t find what he wanted amid the pandemic vehicle shortages.

From The Wall Street Journal Jun. 6, 2026

I was born on March 9, 1943 in Chicago, Ill. U.S.A.

From "Endgame" by Frank Brady

To remedy these ills, the court needs top-to-bottom reform.

From Slate Jul. 29, 2026

As Dan Kois illustrates in this ode to kicking back with friends, spending unstructured time together is a blessedly simple cure to the ills of modern life.

From Slate Jul. 10, 2026

In the video, Pratt stood outside Raman’s Silver Lake home and the city-owned Getty House in Hancock Park, where Bass lives, contending both are far removed from the urban ills that beset other Angelenos.

From Los Angeles Times May 21, 2026

But at the end, a veiled reference to the need to "support victims of some of the ills that, so tragically, exist in both our societies today".

From BBC Apr. 29, 2026

He was fed up with traveling through exotic countries selling shark-fin aphrodisiacs, ginseng to cure all ills, carved Eskimo statues, stuffed Amazonian piranhas, and chinchillas for ladies’ coats.

From "The House of the Spirits: A Novel" by Isabel Allende

"If you have a generally iller population, that's not good for the residents, it's not good for productivity, it's not good for the economy.'"

From BBC May 25, 2023

This gave him an unnatural appearance and made him look iller than ever.

From The New Yorker Dec. 30, 2019

He got iller and iller and iller, and of course he died in the beginning of 2015 when some of the other things had started appearing in the press.

From BBC Nov. 23, 2016

Still, in his older, iller years, he's become kinder, even to himself, and though he wished he'd done some stuff better, he could live with it.

From The Guardian Jun. 23, 2012

She is evidently much iller than I thought.

From Victor's Triumph Sequel to A Beautiful Fiend by Southworth, Emma Dorothy Eliza Nevitte

The Black neighborhoods like Baldwin Hills Estates, Ladera Heights and View Park all sit hillside with some of the illest views in the city.

From Los Angeles Times Apr. 13, 2026

His wife was told she should prepare for the worst, with staff describing her husband as "one of the illest people they'd ever seen".

From BBC May 21, 2024

Rapper Travis Scott told his nearly 12 million followers on X, the site formerly known as Twitter, that Monday “might be one for the illest days in women’s sports historyyyyyyy.”

From Seattle Times Apr. 2, 2024

Blaze is just one of the illest low heads.

From Salon Mar. 6, 2021

A lingring death maye auaile my soule, but it is the illest of ills that can befortune my bodie.

From The Vnfortunate Traveller, or The Life Of Jack Wilton With An Essay On The Life And Writings Of Thomas Nash By Edmund Gosse by Gosse, Edmund

These animals also performed worse on tasks that tested their ability to remember where food had been located.

From Science Daily Jul. 29, 2026

For many working parents, she said, this was made worse by expensive nursery fees and the cost of covering children's hot lunches and after school clubs.

From BBC Jul. 29, 2026

The contrasts become worse in looking at Vance and Obama’s second books, both of which were more obviously written with an eye toward running for higher office.

From Salon Jul. 29, 2026

But the carmaker issued a shock profit warning last month, saying that business in China was proving even worse than expected amid fierce competition and a sluggish economy.

From Barron's Jul. 29, 2026

That stitch in my side on my second hill run was ten times worse, and that went away no problem.

From "Keeping Pace" by Laurie Morrison

Isabel Díaz Ayuso, the leader of Madrid’s local government, earlier this week described the Madrid wildfires as perhaps “the worst natural catastrophe in Spain’s history.”

From The Wall Street Journal Jul. 29, 2026

As French firefighters struggle to contain the worst wildfires in living memory with just 12 aerial water bombers, production of the iconic aircraft creaks along half a world away in a Canadian factory.

From Barron's Jul. 28, 2026

Even the best possible course is going to be one of the worst diseases most children ever go through.

From Los Angeles Times Jul. 28, 2026

"People say your 20s are the best years of your life and these are the worst years of my life, by far."

From BBC Jul. 28, 2026

“This was the reason we were sent here. Not to be the worst partner team in the history of forever, but because you and I are supposed to fix this.”

From "Glitch" by Laura Martin

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