Etymograph

English

lethal

Lethal comes from Latin lētālis ‘deadly, mortal, fatal’, and goes back to lētum ‘death’.

  1. Latinc. 75 BCE–200 CElētum1‘death’
  2. Latinc. 75 BCE–200 CElētālis1‘deadly, mortal, fatal’
  3. Englishearliest quotation 2013lethal1

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, English lethal
  2. Earliest quotation in Wiktionary’s entry: 2013, Old soldiers?: “Whether modern, industrial man is less or more warlike…”.

Earlier history uncertain. See Wiktionary.

Lineage

  1. Latinc. 75 BCE–200 CElētumWiktionary, English lethal‘death’
  2. Latinc. 75 BCE–200 CElētālisWiktionary, English lethal‘deadly, mortal, fatal’
  3. Englishearliest quotation 2013lethalWiktionary, English lethal. Earliest quotation in Wiktionary’s entry: 2013, Old soldiers?: “Whether modern, industrial man is less or more warlike…”

The story

Learned borrowing from Latin lētālis (‘deadly, mortal, fatal’), improperly written lēthālis, from lētum (‘death’), improperly written as lēthum, from a supposed connection with Ancient Greek λήθη (lḗthē, “oblivion, forgetfulness”).

Full etymology on Wiktionary

Linked words

through Proto-Indo-European *ley- ‘to flow’

liver, lin, littoral, 1 more

Today it means

adj Of, pertaining to, or causing death; deadly; mortal; fatal.

Sources

Sources: Wiktionary, “lethal”. 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 / Latin lētum / lethal

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