Killer cancel - A term most often used by stamp collectors in referring to a heavy cancellation that covers a postage stamp’s design.

KKL - (Hebrew: Keren Kayemeth Leyisrael) - JNF - Jewish National Fund - Fund established by the Fifth Zionist Congress in 1901 to purchase land in the land of Israel and further its settlement. JNF was originally funded entirely by contributions of private citizens. One month after the fund was established, Yona Krementzky was appointed as head of the JNF. Krementzky tried different methods of raising money, such as publishing JNF stamps, the proceeds of which went into the fund. These stamps were affixed to official Zionist documents as well as personal letters, and many people collected them. The first stamp was issued in 1902 and showed the Star of David and the name "Zion". JNF stamps (labels) were used during the Interim Period (May 1948) as postage stamps after the word "Doar" (Post) was overprinted.

Kreuzer - 1/60 of the Gulden, the official currency of the Austrian Empire and later the Austro-Hungarian Empire, 1754-1892. The currency was decimalized in 1857 resulting in a new currency system with 100 Kreuzer equaling 1 Gulden.

KBA - (Kohot Bitahon Arzeem) National Defense Force. Generally a triangular cachet including the Hebrew letters Kaf, Beit, Alef and a number of the unit to which the cachet was designated.

Kaplove - "Stamp catalogue of the Jewish National Fund" - Published 1973 by JNF education fund & SIP