Jerusalem Cross - Also known as the Crusaders' cross, is a Christian symbol consisting of a large Greek cross surrounded by four smaller Greek crosses, one in each quadrant. In Holy Land philately, a cachet used in Jerusalem by officials of the French Post to mark mail originating from Jerusalem between the years 1858 and 1879.

JNF - Jewish National Fund - (Hebrew: Keren Kayemeth Leyisrael, KKL) - 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 from 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.

Jubilee line - Colored line framing stamps in sheet margin.

Julian Calendar - A calendar introduced in Rome in 46 BCE by Julius Caesar establishing the 12-month year of 365 days, with each fourth year having 366 days and the months each having 31 or 30 days except for February which has 28 or, in leap years, 29 days. The Julian calendar was in use until 1918/19 in Eastern European countries like Russia, Bulgaria, Romania and the Eastern Orthodox Church; the Julian dates were behind the Gregorian calendar, 11 days after 1700, 12 days after 1800 and 13 days after 1900.