A transuranic element of atomic number 104, symbol Ku; also called rutherfordium, symbol Rf. It is produced in very small quantities by nuclear reactions. In November 1993 the nomenclature committe of the American Chemical Society approved the name rutherfordium for element 104. Russsian investigators who claim to have first discovered element 104, isotope 260 (half-life 0.3 seconds) in 1964 at Dubna proposed the name kurchatovium. However, investigators at Berkely in 1969 produced several isotopes of element 104 but were unable to produce isotope 260; they reported finding isotope 257, with a half-life of 4-5 seconds, isotope 259 with a half-life of 3-4 seconds, and isotope 258 with a shorter half-life.  [WordNet 1.5]