ENGLISH
REFERENCE

ill

adj. · adv. · n.
US //ˈɪɫ// UK //ˈɪl// ill
  1. 1 bad or harmful (adj.)
    B2 Upper Intermediate Formal

    bad, harmful, or showing that you do not like someone.

    harmful, hostile, or unfavorable in nature; often used in fixed expressions regarding intentions or effects.

    Example

    I hope you don't have any ill feelings toward me after our argument.

    Example

    The sudden closure of the factory had an ill effect on the local economy, leading to a sharp rise in unemployment.

  2. 2 cool or great (adj.)
    C1 Advanced Slang

    very good, impressive, or cool.

    highly impressive or excellent; a reversal of the literal meaning common in urban vernacular.

    Example

    That new song has an ill beat.

    Example

    The dancer performed an ill sequence of power moves that left the entire audience in shock.

Show 2 more sensesShow fewer
  1. 3 badly or poorly (adv.)
    B2 Upper Intermediate Formal

    badly or not enough.

    in a poor, inadequate, or unfavorable manner; frequently used as a prefix in compound adjectives.

    Example

    The soldiers were ill-prepared for the cold winter weather.

    Example

    The company was ill-equipped to handle such a massive influx of customer complaints during the holiday season.

  2. 4 problems or harm (n.)
    C1 Advanced Literary Formal

    problems, troubles, or things that cause suffering.

    problems, misfortunes, or social ailments; often used in the plural to describe broad issues.

    Example

    The politician promised to fix the many ills of modern society.

    Example

    The philosopher argued that greed was the root of all social ills, poisoning the relationships between different classes.

Origin

From Middle English ille, an adjective meaning "evil; wicked", from Old Norse íllr (adjective), ílla (adverb), and ílt (noun). The Norse forms descend from Proto-Germanic \ilhilaz, which in turn derives from Proto-Indo-European \h₁elḱ-, a root meaning wound or ulcer: Latin ulcus ("sore"), Ancient Greek ἕλκος hélkos ("wound, ulcer"), and Sanskrit अर्शस् árśas ("hemorrhoids") all share this origin.

The cognates have kept rougher company than English ill. Scots and Yola preserve ill in the same spelling; Danish has ilde ("bad"), Norwegian ille ("bad") in both standard forms, Swedish illa ("badly; poorly"), and Faroese and Icelandic share illur ("bad, ill, wicked"). The semantic range across Germanic suggests the word carried moral and physical senses from the start: a wound, a wrong, a thing that festers.

Idioms7 entries

© 2026 English Reference