Sentence:  The development of these projectors was spurred During World War II, the Soviet Union fired <WSD>Katyusha</WSD> rockets from the ground or truck mounted racks. The standard <WSD>Katyushas</WSD> were 6 feet long, weighed 92.5 pounds, and had a range of 3 miles. 
Meaning of the word marked with <WSD> tags:  A type of rocket which can be launched from a Katyusha.