K

Kaffirs
169;

Katie bar the door
8; The phrase "Katie bar the door!" (also as "Katie bar the gate!"; sometimes written as Katy) is a very American exclamation, more common in the South than elsewhere, meaning that disaster impends—“watch out”, “get ready for trouble” or “a desperate situation is at hand”. From WorldWideWords.org

Keeley Cure
Devised by Leslie Keeley, this was a proprietary system of treatment for the alcohol and opium habits. The Keeley Cure was a forerunner of certain measures adopted by Alcoholics Anonymous. Relying heavily on injections of Bichloride of Gold (a chemical impossibility), it was so well-known in its day that several popular songs, such as an Irish comic song, entitled "The Keeley Cure," parodied it unmercifully. More on Wikipedia

Khartoum
29;

Khäutsch, Max
47; a captain in the Trabants, and field chief of K&K Special Security, who had "proven himself useful at home as an assassin"

Kimura, Mr.
29;

Klu Klux Klan ("KKK")
7; the name of a number of past and present fraternal organizations in the United States that have advocated white supremacy, anti-Semitism, racism, anti-Catholicism, homophobia, and nativism; 178; Wikipedia entry

Kepler
115;

Kieselguhr Kid
171; "notorious dynamiter of the San Juans"; Dynamite, a blasting explosive, was invented in 1867 by Alfred P. Nobel by mixing nitroglycerin with kieselguhr, a porous silica-containing earth, in proportions that left an essentially dry and granular material, producing a solid that was resistant to shock but readily explodable by heat or sudden impact.