Bolt, Usain, 1986-, Jamaican sprinter. Unusually tall (6 ft 5 in./1.96 m) for his sport, he won the gold medal for the 200-m sprint at the 2002 world junior championships (WJC), and broke the record he set at the next two WJCs. Recovering from injury, he did poorly in the 2004 Olympics, but won gold in the 200-m at the 2007 world championships and ran a record 100-m sprint in 2008. At the 2008 Olympics, Bolt won gold in all the events he entered, the 100-m and 200-m sprints and the 400-m relay. He was the first Olympic athlete to set world records in all those events, and broke his 100-m and 200-m records at the 2009 world championships.

Type of breech mechanism that was key to developing an effective repeating rifle. It combines the firing pin, a spring, and an extractor, all housed in or attached to the bolt. A projecting handle with a round knob moves the bolt back and forth. As the bolt is thrust forward, it pushes a cartridge into the chamber and cocks the piece. The trigger releases the spring-driven firing pin inside the bolt. After firing, the extractor on the head of the bolt removes the spent cartridge and ejects it. The bolt then moves a new cartridge from the magazine.

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Mechanical fastener, usually used with a nut, for connecting two or more parts. Bolted joints can be readily disassembled and reassembled; hence bolts or screw fasteners are used more than other types of mechanical fastener. A bolt consists of a head and a cylindrical body with screw threads along a portion of its length. Nuts have internal (or female) threads to match those of the bolt. Washers are often used to prevent loosening and crushing.

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Bolt usually refers to a type of fastener.

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