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)