Etymograph

English

nocuous

Nocuous comes from Latin nocuus ‘harmful’, from noceō ‘to harm, damage’, and ultimately from Proto-Indo-European *neḱ- ‘to perish, disappear’.

  1. Proto-Indo-Europeanc. 4500–2500 BCE*neḱ-1‘to perish, disappear’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*noḱéyeti1‘to make disappear, to cause death’reconstructed
  3. Proto-Italicc. 1500–700 BCE*nokeō1‘to harm, hurt, injure’reconstructed
  4. Latinc. 75 BCE–200 CEnoceō1‘to harm, damage’
  5. Latinc. 75 BCE–200 CEnocuus2‘harmful’
  6. Englishtodaynocuous2

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, Latin nocuus
  2. 2 Wiktionary, English nocuous

Lineage

  1. Proto-Indo-Europeanc. 4500–2500 BCE*neḱ-Wiktionary, Latin nocuus‘to perish, disappear’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*noḱéyetiWiktionary, Latin nocuus‘to make disappear, to cause death’reconstructed
  3. Proto-Italicc. 1500–700 BCE*nokeōWiktionary, Latin nocuus‘to harm, hurt, injure’reconstructed
  4. Latinc. 75 BCE–200 CEnoceōWiktionary, Latin nocuus‘to harm, damage’
  5. Latinc. 75 BCE–200 CEnocuusWiktionary, English nocuous‘harmful’
  6. EnglishtodaynocuousWiktionary, English nocuous

Linked words

through Proto-Indo-European *neḱ- ‘to perish, disappear’

nectar, obnoxious, necropolis, internecine, 18 more

through Latin noceō ‘to harm, damage’

innocent, nuisance, innocence, noxious, 13 more

Today it means

adj Likely to cause harm or damage.

Sources

Sources: Wiktionary, “nocuous”; the older steps come from the Wiktionary entry for Latin nocuus. 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 *neḱ- / nocuous

Shirt and support for this word