unk-unk n. especially in engineering, something, such as a problem, that has not been and could not have been imagined or anticipated; an unknown unknown. Editorial Note: The Barnhart Dictionary of New English Since 1963 (Barnhart/Harper & Row, New York, 1973) gives this term as a plural and defines it as “a series of unknowns, especially of inexplicable calamities.” The term is now common as a singular and has spread from the aerospace engineering business to be used in military, government, and corporate environments. The two letter Ks are not silent as they would be in unknown, but are audible and hard, as in the end of drunk. (source: Double-Tongued Dictionary)
Further reading
Twice a day the River Thames recedes, revealing a muddy shoreline. Hobbyists known as mudlarks stroll the surface searching for objects that have found their way into the river over the centuries, everything from ancient Roman jewelry to modern...
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...