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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:

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

From Science Daily Jul. 25, 2026

Some have children, elderly or ill family members to care for during the day and, more importantly, it pays better.

From BBC Jul. 24, 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

One firefighter died after falling ill while battling the flames in Sicily, the interior minister said.

From Barron's Jul. 24, 2026

At a Fourth of July celebration, US President Zachary Taylor fell ill, was diagnosed with cholera, and died five days later.

From "American Spirits" by Barb Rosenstock

“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 goals and assists are really important so I'll make sure I'm right at it," she adds.

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

I’ll always feel it; it’s always there, just below the surface.

From "Split the Sky" by Marie Arnold

"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

"She was only 28. It wasn't like she was ill. She was here one day and gone the next, we didn't even get to say goodbye."

From BBC Aug. 8, 2025

“I walked into the facility healthy and feeling fine, and within 24 hours I became severely ill. I had severe burning in my face, tremors, twitching; I felt like I was being electrocuted.”

From Los Angeles Times Mar. 12, 2025

Another shares: "When I see someone making really small repetitive movements, such as my husband bending his toes, I feel physically ill. I hold it back but I want to vomit."

From BBC Dec. 12, 2024

"They may not mean me ill. Men have looked at women since time began, perhaps it is no more than that."

From "A Clash of Kings" by George R.R. Martin

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

From MarketWatch Jul. 27, 2026

Grand Detour, Ill.: John Deere’s “self-polishing” steel blade allowed settlers to slice through the sticky Midwest sod, unlocking the agricultural potential of the American heartland.

From The Wall Street Journal Jul. 9, 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 North Chicago, Ill., company has said it expects combined revenue from Rinvoq and fellow autoimmune drug Skyrizi will top $31 billion this year.

From The Wall Street Journal Jun. 22, 2026

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

From "Endgame" by Frank Brady

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

An experience completely ignorant to the ills of modern football, to politics, ticket prices or hydration breaks.

From BBC Jun. 21, 2026

The Swiss are largely well-governed, and the country’s appeal is understandable to people who want to escape the tax rates and other ills that are common elsewhere in Europe.

From The Wall Street Journal Jun. 14, 2026

But Gouzer said he expects Banksy’s market to keep rebuilding, thanks to a fresh influx of younger tech collectors and international wild-card buyers who admire the roguish way Banksy skewers societal ills.

From The Wall Street Journal May 21, 2026

Without proper training and conditioning—and sometimes even with them—competitive rowers are apt to experience a wide variety of ills in the knees, hips, shoulders, elbows, ribs, neck, and above all the spine.

From "The Boys in the Boat: Nine Americans and Their Epic Quest for Gold at the 1936 Berlin Olympics" by Daniel James Brown

"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

Last year began with my being ill, kept on with my being iller, then I was unwell, followed by being poorly with a tiny interlude of infirmity.

From The Guardian Aug. 15, 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

Not knowing is worse than the very illest news.

From Grey Town An Australian Story by Baldwin, Gerald

The Times quoted an unnamed "senior football figure" calling the plan "potentially much worse than the European Super League", as it would have an impact on all levels of football across the globe.

From Barron's Jul. 28, 2026

There is nothing worse than needing to see a doctor but finding there are no appointments after spending an hour hanging on the phone.

From BBC Jul. 28, 2026

“It couldn’t come at a worse time, as a lot of producers will be selling their calves over the next few months.”

From MarketWatch Jul. 28, 2026

When his children complain about a newspaper article, he reminds them that he endured worse at their age, when he was fighting bruising corporate battles.

From The Wall Street Journal Jul. 27, 2026

Even worse was the way she behaved towards Tall Tailless.

From "Wolf Brother" by Michelle Paver

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

Monday’s announcement appeared to leave investors uneasy as well, following hopes that the worst of the culture-war fallout from the logo change was in the rearview.

From MarketWatch Jul. 28, 2026

France has seen its worst fires in two decades, while officials in the Spanish capital Madrid say they are the worst the region has ever experienced.

From BBC Jul. 27, 2026

And if Emma’s dad is in prison…my brain starts imagining the worst.

From "South of Somewhere" by Kalena Miller

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