The whole nine yards

"The whole nine yards" or "the full nine yards" is a colloquial American English phrase meaning "everything, the whole lot" or, when used as an adjective, "all the way", as in, "The Army came out and gave us the whole nine yards on how they use space systems." Its origin is unknown and has been described by Yale University librarian Fred R. Shapiro as "the most prominent etymological riddle of our time".