lunacy

/ˈluːnəsi/ (bre, ipa) · /ˈluːnəsi/ (ame, ipa) · /ˈlü-nə-sē/ (ame, mw)

lunacy — noun

1. an action or plan that seems so silly or reckless that doing it is almost certai

1.名詞C1
釋義

an action or plan that seems so silly or reckless that doing it is almost certain to lead to a bad outcome — for instance, quitting a steady job with no savings, or driving across a frozen lake in spring.

例句

Paloma called it sheer lunacy to invest her savings in an untested startup.

collocation: sheer lunacy

It would be lunacy to drive across the mountain pass during the snowstorm tonight.

pattern: it would be lunacy to + infinitive

同義詞
  • madness

    near-equivalent in this sense; slightly more common and less old-fashioned.

  • folly

    more formal and literary; emphasises lack of wisdom over outright recklessness.

  • insanity

    stronger; suggests the action is shocking, not merely unwise.

反義詞
  • wisdom

    the considered, sensible opposite.

  • prudence

    more formal; emphasises caution and foresight.

文法句型

it would be lunacy to + infinitive

the lunacy of + noun/-ing

用法筆記

Often used as an exclamation or strong evaluation of someone else's choice ('That's lunacy!'). Frequently modified by intensifiers — sheer, pure, complete, absolute — and by domain adjectives like economic, political, financial.

常見錯誤

❌She did a lunacy yesterday.
✅What she did yesterday was lunacy.
💡'lunacy' names the quality of the action, you don't 'do' a lunacy.
❌It is lunacy that he refused the offer.
✅It was lunacy to refuse that offer.
💡prefer the 'it is lunacy to + infinitive' frame for judging a specific decision.

2. a severely disturbed state of mind, treated as a legal or historical category fo

2.名詞C2
釋義

a severely disturbed state of mind, treated as a legal or historical category for someone unable to act with reason — now an outdated and offensive label, kept only in fixed phrases such as historical statute names.

例句

The 1845 Lunacy Act let courts commit patients to asylums without a family hearing.

fixed historical phrase: the Lunacy Act / Lunacy Commission

Beatrix studied old hospital records that classified depression as a form of lunacy.

historical legal usage

同義詞
  • insanity

    still used as a legal term ('insanity defence'); the modern equivalent in courtroom language.

  • madness

    broader and still current in informal speech; less tied to legal procedure.

反義詞
  • sanity

    the standard opposite, both in everyday and legal contexts.

文法句型

a plea of lunacy

the lunacy laws

用法筆記

Distinguish from sense 1: this sense names a clinical or legal state of someone, whereas sense 1 names a foolish action by an otherwise rational person. In modern English the medical sense is offensive and only survives in historical phrases (Lunacy Act, lunacy hearing); never apply it to a living person.

常見錯誤

❌My uncle was diagnosed with lunacy last year.
✅My uncle was diagnosed with severe bipolar disorder last year.
💡'lunacy' as a medical label is archaic and offensive; use the modern clinical term.