Artificial intelligent assistant

pierceless

pierceless, a. rare.
  (ˈpɪərslɪs)
  [f. pierce v. + -less; cf. dauntless, quenchless, etc.]
  Incapable of being pierced; impenetrable. So ˈpiercelessness, impenetrability.

1674 N. Fairfax Bulk & Selv. 108 We cannot tear from it piercelessness or impenetrability, which is the closest sticker to a body. 1755 J. G. Cooper Tomb Shakspeare Sel. Poems (1762) 149 Sharp spears in pierceless phalanx reared.

Oxford English Dictionary

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