adjective, worse, worst; ill·er, ill·est for 7.




    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

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.


Origin of ill.

(def 4) < Latin illustrissimus




contraction of I will.
Can be confusedaisle I'll isle

Usage note Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for ill

Contemporary Examples of ill

Historical Examples of ill

British Dictionary definitions for ill


adjective worse or worst

(usually postpositive) not in good health; sick
characterized by or intending evil, harm, etc; hostileill deeds
causing or resulting in pain, harm, adversity, etcill effects
ascribing or imputing evil to something referred toill repute
promising an unfavourable outcome; unpropitiousan ill omen
harsh; lacking kindnessill will
not up to an acceptable standard; faultyill manners
ill at ease unable to relax; uncomfortable


evil or harmto wish a person ill
a mild disease
misfortune; trouble


badlythe title ill befits him
with difficulty; hardlyhe can ill afford the money
not rightlyshe ill deserves such good fortune

Word Origin for ill

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


abbreviation for



contraction of

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

Word Origin and History for ill

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

ill in Medicine




Not healthy; sick.
Not normal, as a condition; unsound.


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 ill


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.