Etymograph

English

illegal

Illegal comes from French illégal, from Medieval Latin illegalis, from in- ‘not’ + lēgālis ‘legal’, from lēx ‘law’.

  1. Proto-Italicc. 1500–700 BCE*lēks1‘law’reconstructed
  2. Latinc. 75 BCE–200 CElēx2‘law’
  3. Latinc. 75 BCE–200 CElēgālis3‘legal’
  4. Medieval Latinc. 600–1500illegalis3
  5. Frenchc. 1600–presentillégal3‘illegal’
  6. Englishearliest quotation c. 1650illegal3

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, Latin lex
  2. 2 Wiktionary, Latin legalis
  3. 3 Wiktionary, English illegal
  4. Earliest quotation in Wiktionary’s entry: c. 1650, John Spalding, Aberdeen: T. Evans: “That whatſoever illegals hath been uſed againſt his friends…”.

Lineage

  1. Proto-Italicc. 1500–700 BCE*lēksWiktionary, Latin lex‘law’reconstructed
  2. Latinc. 75 BCE–200 CElēxWiktionary, Latin legalis‘law’
  3. Latinc. 75 BCE–200 CElēgālisWiktionary, English illegal‘legal’
  4. Medieval Latinc. 600–1500illegalisWiktionary, English illegal
  5. Frenchc. 1600–presentillégalWiktionary, English illegal‘illegal’
  6. Englishearliest quotation c. 1650illegalWiktionary, English illegal. Earliest quotation in Wiktionary’s entry: c. 1650, John Spalding, Aberdeen: T. Evans: “That whatſoever illegals hath been uſed againſt his friends…”

The story

In senses relating to immigration, via clipping of illegal alien or illegal immigrant.

Full etymology on Wiktionary

Linked words

through Proto-Indo-European *legʰ- ‘to lie’

law, low, lie, lawyer, fellow, layer, log, litter, ledger, lair, ledge, lawless, 25 more

through Latin lex ‘the legal machinery of a state, the law’

college, lay, legacy, colleague, delegation, delegate, collegiate, 12 more

through Latin legalis ‘legal’

loyalty, loyal, 5 more

Today it means

adj Contrary to, forbidden, or not authorized by law, especially criminal law.

Sources

Sources: Wiktionary, “illegal”; the older steps come from the Wiktionary entries for Latin lex, Latin legalis. 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-Italic *lēks / illegal

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