On the little metal covers in the street for cable phone/TV cables, they all say C.A.T.V. I expect the c is for cable and the TV is obvious, but what does the A stand for?
so there's no confusion - CATV (the computer networking cable) is different and actually means CATegory 5 cable (full name is CATV UTP which means cat5 untwisted pair)
Used to be in the tv trade. These systems date back to the 60s when they where used for distributing the normal channels in areas of poor reception - long before today's multi channel systems. Did a little bit of checking to confirm, American Heritage Dictionary agrees, as does this page:
http://www.its.bldrdoc.gov/fs-1037/dir-006/_0778.h tm