A.Word.A.Day–Today’s Word (In case the link has changed, here’s their definition, which I LOVED):
octothorpe (OK-tuh-thorp) noun
The symbol #.
[The symbol # is derived from a shorthand way of writing lb, the abbreviation for the Latin libra (balance), just as $ is a shorthand way of writing US. Octothorpe is an alteration, influenced by octo-, of earlier octalthorpe, probably a humorous blend of octal (an eight-point pin used in electronic connections) and someone whose last name was or ended in “thorpe”, and whose identity is subject to speculation. It may be James Edward Oglethorpe, an eighteenth century English philanthropist, but more likely it is an Olympic athlete, Jim Thorpe. In the early 1960s, Bell Labs introduced two special keys in its innovative touch-tone telephone keypads, “#” and “*”, for which it needed fresh names. Having eight points, “octo-” was an obvious first element. Since the engineer involved in introducing this innovation was active in a group seeking the return of Jim Thorpe’s medals from Sweden, he whimsically added “-thorpe”, creating octothorpe. (Jim Thorpe was disqualified because of his professional status, but his medals were restored posthumously.) The “#” is also known as a pound sign, crosshatch, number sign, sharp, hash, crunch, mesh, hex, flash, grid, pig-pen, gate, hak, oof, rake, fence, gate, grid, gridlet, square, and widget mark.]
Some other eight-based words, other than the obvious octagon, octave, and octopus, are octamerous, having eight parts or organs; octane, a type of hydrocarbon in fuel and solvents; octant, the eighth part of a circle; octonare and octapody, a verse of eight feet; and octonary, pertaining to the number eight.
“In Boise, Idaho, US West is testing a system it calls Voice Interactive Phone, or VIP. By dialing the octothorpe (#) and 44, then saying ‘Messages,’ a subscriber can retrieve voice mail.” Gene Bylinsky and Alicia Hills Moore; Fortune (New York); At Last! Computers You Can Talk to; May 3, 1993.