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adjective, worse, worst; ill·er, ill·est for 7.
  1. of unsound physical or mental health; unwell; sick: She felt ill, so her teacher sent her to the nurse.
  2. objectionable; unsatisfactory; poor; faulty: ill manners.
  3. hostile; unkindly: ill feeling.
  4. evil; wicked; bad: of ill repute.
  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.
  1. an unfavorable opinion or statement: I can speak no ill of her.
  2. harm or injury: His remarks did much ill.
  3. trouble, distress, or misfortune: Many ills befell him.
  4. evil: to know the difference between good and ill.
  5. sickness or disease.
  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.
  1. ill at ease, socially uncomfortable; nervous: They were ill at ease because they didn't speak the language.

Origin of ill

1150–1200; Middle English ill(e) (noun and adj.) < Old Norse illr (adj.) ill, bad
Can be confusedill sick1 (see synonym study at the current entry)

Synonyms for ill

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Synonym study

1. 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. 4. See bad1.

Antonyms for ill

1. well, healthy. 4. good.

Grammar note

See well1. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for ills

Contemporary Examples of ills

Historical Examples of ills

  • I fear no foe, with Thee at hand to bless: Ills have no weight, and tears no bitterness.

  • It was and is intended by her for the stomachs of men, to cure all the ills of mankind.

  • Pat is more occupied with the bright present than with past ills.

    The Elm Tree Tales

    F. Irene Burge Smith

  • And the soul which we behold is in a similar condition, disfigured by ten thousand ills.

  • My head so pillowed and a saint from Heaven ministering to my ills?


    Raphael Sabatini

British Dictionary definitions for ills


adjective worse or worst
  1. (usually postpositive) not in good health; sick
  2. characterized by or intending evil, harm, etc; hostileill deeds
  3. causing or resulting in pain, harm, adversity, etcill effects
  4. ascribing or imputing evil to something referred toill repute
  5. promising an unfavourable outcome; unpropitiousan ill omen
  6. harsh; lacking kindnessill will
  7. not up to an acceptable standard; faultyill manners
  8. ill at ease unable to relax; uncomfortable
  1. evil or harmto wish a person ill
  2. a mild disease
  3. misfortune; trouble
  1. badlythe title ill befits him
  2. with difficulty; hardlyhe can ill afford the money
  3. not rightlyshe ill deserves such good fortune

Word Origin for ill

C11 (in the sense: evil): from Old Norse illr bad
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

Word Origin and History for ills



c.1200, "morally evil" (other 13c. senses were "malevolent, hurtful, unfortunate, difficult"), from Old Norse illr "ill, bad," of unknown origin. Not related to evil. Main modern sense of "sick, unhealthy, unwell" is first recorded mid-15c., probably related to Old Norse idiom "it is bad to me." Slang inverted sense of "very good, cool" is 1980s. As a noun, "something evil," from mid-13c.



early 13c., "to do evil to," from ill (adj.). Meaing "to speak disparagingly" is from 1520s. Related: Illed; illing.



c.1200, "wickedly; with hostility;" see ill (adj.). Meaning "not well, poorly" is from c.1300. It generally has not shifted to the realm of physical sickess, as the adjective has done. Ill-fated recorded from 1710; ill-informed from 1824; ill-tempered from c.1600; ill-starred from c.1600. Generally contrasted with well, hence the useful, but now obsolete or obscure illcome (1570s), illfare (c.1300), and illth.

Online Etymology Dictionary, © 2010 Douglas Harper

ills in Medicine


  1. Not healthy; sick.
  2. Not normal, as a condition; unsound.
  1. A disease or illness, especially of animals.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Idioms and Phrases with ills


In addition to the idioms beginning with ill

  • ill at ease
  • ill wind that blows no one any good, it's an

, also see under

  • get sick
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.