The Spanish word `real' (which has two syllables: /ray-ahl'/) means `royal'; El Camino Real is `the royal road'. In the FORTRAN language, a `real' quantity is a number typically precise to seven significant digits, and a `double precision' quantity is a larger floating-point number, precise to perhaps fourteen significant digits (other languages have similar `real' types).
When a hacker from MIT visited Stanford in 1976, he remarked what a long road El Camino Real was. Making a pun on `real', he started calling it `El Camino Double Precision' -- but when the hacker was told that the road was hundreds of miles long, he renamed it `El Camino Bignum', and that name has stuck. (See bignum.) In recent years, the synonym `El Camino Virtual' has been reported as an alternate at IBM and Amdahl sites in the Valley.
[GLS has since let slip that the unnamed hacker in this story was in fact he --ESR]