impervious

 
Pronunciation: /ɪmˈpəːvɪəs/

adjective

  • 1not allowing fluid to pass through: an impervious layer of basaltic clay
  • 2 (impervious to) unable to be affected by: he worked, apparently impervious to the heat

Derivatives

imperviously

adverb

imperviousness

noun

Origin:

mid 17th century: from Latin impervius (from in- 'not' + pervius 'pervious') + -ous