unknown unknown

短语

词形变化

unknown unknowns 复数 unknown unknowns

释义与例句

n.
  1. 1.

    An uncertainty of unknown magnitude, consequence, structure, and probability characteristics, possibly with completely unsuspected existence; something that we don't know that we don't know.

词源

Popularized by Donald Rumsfeld in 2002, though used much earlier.

来源：wiktionary