Why Do They Call Themselves "Hams"?
"Ham: a poor operator. A 'plug.'"
That's the definition of the word given in G. M. Dodge's "The Telegraph
Instructor" even before there was radio. The definition has never changed in
wire telegraphy. The first wireless operators were landline telegraphers who
left their offices to go to sea or to man the coastal stations. They brought
with them their language and much of the tradition of their older profession. In
those early days, every station occupied the same wavelength-or, more accurately
perhaps, every station occupied the whole spectrum with its broad spark signal.
Government stations, ships, coastal stations and the increasingly numerous
amateur operators all competed for time and signal supremacy in each other's
receivers. Many of the amateur stations were very powerful. Two amateurs,
working each other across town, could effectively jam all the other operations
in the area. Frustrated commercial operators would refer to the ham radio
interference by calling them "hams." Amateurs, possibly unfamiliar with the real
meaning of the term, picked it up and applied it to themselves in true "Yankee
Doodle" fashion and wore it with pride. As the years advanced, the original
meaning has completely disappeared.
From ARRL www.hello-radio.org