cleanskin
n.— «The Times said that at least two of the men had just returned from Pakistan, but none were on the files of security services. This meant they were “cleanskins”—intelligence parlance for terrorists with no previously known link to suspicious groups, and thus incredibly hard to track down before they strike.» —“Model citizens, ruthless killers” in London, England TodayOnline (Singapore) July 14, 2005. (source: Double-Tongued Dictionary)
Further reading
What if, instead of being an inanimate object, a dictionary were alive? That’s the idea behind a lavishly illustrated new children’s book called The Dictionary Story (Bookshop|Amazon) by Oliver Jeffers and Sam Winston. This is part of a...
Astronauts returning from space say they experience what’s called the overview effect, a new understanding of the fragility of our planet and our need to reflect on what humans all share as a species. A book about the end of the universe...