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undocumented vs. illegal

[uhn-dok-yuh-men-tid] / ʌnˈdɒk yəˌmɛn tɪd /

adjective

  1. lacking documentation or authentication.

  2. lacking proper immigration or working papers: undocumented immigrants.

    an undocumented worker;

    undocumented immigrants.

[ih-lee-guhl] / ɪˈli gəl /

adjective

  1. forbidden by law or statute.

    Synonyms:
    unlicensed , illicit , illegitimate , unlawful
  2. contrary to or forbidden by official rules, regulations, etc..

    The referee ruled that it was an illegal forward pass.

noun

  1. Informal: Disparaging and Offensive.  illegal alien.