Etymograph

English

lunatic

Lunatic comes from Late Latin lunaticus ‘moonstruck’, from Latin luna ‘moon’, and ultimately from Proto-Indo-European *lewk- ‘bright’.

  1. Proto-Indo-Europeanc. 4500–2500 BCE*lewk-1‘bright’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*lówksneh₂1‘moon’reconstructed
  3. Proto-Italicc. 1500–700 BCE*louksnā1‘moon’reconstructed
  4. Latinc. 75 BCE–200 CEluna2‘moon’
  5. Late Latinc. 200–600 CElunaticus2‘moonstruck’
  6. Old Frenchc. 842–1400lunatique2
  7. Middle Englishc. 1150–1500lunatik2‘suffering from madness due to varying lunar phases’
  8. Englishearliest quotation 1902lunatic2

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, Latin luna
  2. 2 Wiktionary, English lunatic
  3. Earliest quotation in Wiktionary’s entry: 1902, Hilaire Belloc: “While there are other races (or individuals—heaven forgive me,…”.

Lineage

  1. Proto-Indo-Europeanc. 4500–2500 BCE*lewk-Wiktionary, Latin luna‘bright’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*lówksneh₂Wiktionary, Latin luna‘moon’reconstructed
  3. Proto-Italicc. 1500–700 BCE*louksnāWiktionary, Latin luna‘moon’reconstructed
  4. Latinc. 75 BCE–200 CElunaWiktionary, English lunatic‘moon’
  5. Late Latinc. 200–600 CElunaticusWiktionary, English lunatic‘moonstruck’
  6. Old Frenchc. 842–1400lunatiqueWiktionary, English lunatic
  7. Middle Englishc. 1150–1500lunatikWiktionary, English lunatic‘suffering from madness due to varying lunar phases’
  8. Englishearliest quotation 1902lunaticWiktionary, English lunatic. Earliest quotation in Wiktionary’s entry: 1902, Hilaire Belloc: “While there are other races (or individuals—heaven forgive me,…”

Linked words

through Proto-Indo-European *lewk- ‘bright’

light, low, link, los, lucy, lea, ounce, lynx, translucent, luminous, lux, lucid, lumen, illuminate, illumination, luminosity, luce, lumia, loach, leucine, lum, luminescent, luminary, luminal, 74 more

through Latin luna ‘moon’

lunar, lune, 13 more

Today it means

noun An insane person.

Sources

Sources: Wiktionary, “lunatic”; the older steps come from the Wiktionary entry for Latin luna. By Wiktionary contributors, CC BY-SA 4.0, via kaikki.org (dump of Oct 3 2026); text adapted and restructured. Language periods are conventional ranges, not dates for this word. License.

Etymograph / Proto-Indo-European *lewk- / lunatic

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