U.S. military slang for the kilometer (about 0.621 mile). Also spelled klick or klik. This unit became popular during the Vietnam War, but it was invented by U.S. troops in Germany during the 1950s. Occasionally it was used as a non-metric unit equal to 1000 yards (0.9144 kilometer).
BTW..thanks for asking Arthur. I spent 3 years in the Corps, 1 in Nam...and never had a clue what a "click" was.
When referring to the numbers that are associated with Mega, Giga and Tera, it's "million", "billion" and "trillion". What's the word that's associated with the next one up, Peta? I vaguely recall a "quadrillion". Not that any country's GNP or national budget/debt will approach a quadrillion yet, but sooner or later... and after all supercomputers are already in the "petaflop" range.