Etymology of ham radio
Ham is an informal term for an amateur radio operator, and, by extension, "ham radio" refers to amateur radio in general. This use of the word first appeared in the United States during the opening decade of the 20th century—for example, in 1909, Robert A. Morton reported overhearing an amateur radio transmission which included the comment: "Say, do you know the fellow who is putting up a new station out your way? I think he is a ham." However, the term did not gain widespread usage in the United States until around 1920, after which it slowly spread to other English-speaking countries.
The term "ham operator" was commonly applied by 19th century landline telegraphers to an operator with poor skills. ("Ham" was also in more general use as a slang word meaning "incompetent", as in the phrases "ham handed" and "ham actor".)
Early radio (initially known as wireless telegraphy) included many former wire telegraph operators, and within the new service "ham" was employed as a pejorative term by professional radiotelegraph operators to suggest that amateur enthusiasts were unskilled. In "Floods and Wireless" by Hanby Carver, from the August, 1915 Technical World Magazine, the author noted "Then someone thought of the 'hams'. This is the name that the commercial wireless service has given to amateur operators..."
Even among amateur radio operators, the term was used pejoratively at first by serious experimenters. For example, in December 1916 QST magazine, an amateur operator working on long distance message passing describes one way to avoid interference was to send messages "...on Thursday nights, when the children and spark coil 'hams' are tucked up in bed" (a spark coil was an unsophisticated radio transmitter, made from an automobile ignition coil, that produced noisy interference).
But only a few months later, in an indication of the changing use of the term among amateurs, a QST writer uses it in a clearly complimentary manner, saying that a particular 16 year old amateur operator "...is the equal of a ham gaining five years of experience by hard luck."
Use of "ham" as a slur by professionals continued, however. A letter from a Western Union Telegraph Company employee, printed in the December, 1919 edition QST, showed familiarity with the word's negative connotations, expressing concern that "Many unknowing land wire telegraphers, hearing the word 'amateur' applied to men connected with wireless, regard him as a 'ham' or 'lid'".
But many other amateurs increasingly adopted the word "ham" to describe their hobby and themselves during this period, embracing the word that was originally an insult, similar to the way Yankee Doodle evolved, as seen, for example, in Thomas F. Hunter's exuberant "I am the wandering Ham" from the January, 1920 issue of QST.
 False etymologies
In spite of—or perhaps because of—its relatively straightforward origin, many interesting and colorful folk etymologies about the supposed origin of "ham" have been developed over the years. Below are some of the competing later explanations that are often charming, but also false.
One alternate explanation is that "ham" is a shortened version of "ham-fisted", meaning incompetent or clumsy. This is a reasonable conjecture, given that all early amateur radio stations used hand-operated telegraph keys to transmit Morse code, and the individual's sending style is referred to as an operator's "fist", so someone who sends badly could be called ham-fisted or ham-handed.
 "A little station called HAM"
This widely circulated but fanciful tale claims that, around 1911, an impassioned speech made by Harvard University student Albert Hyman to the United States Congress, in support of amateur radio operators, turned the tide and helped defeat a bill that would have ended amateur radio activity entirely, by assigning the entire radio spectrum to the military. An amateur station that Hyman supposedly shared with Bob Almy and Peggie Murray, which was said to be using the self-assigned call sign HAM (short for Hyman-Almy-Murray), thus came to represent all of amateur radio. However, this story seems to have first surfaced in 1948, and practically none of the facts in the account check out, including the existence of "a little station called HAM" in the first place.
The 1909 Wireless Registry list in the May edition of Modern Electrics listed Earl C. Hawkins of Minneapolis, Minnesota, as operating with the callsign "H.A.M.", which was likely assigned by the magazine.
 Home Amateur Mechanic magazine
In this version, supposedly HAM was an acronym derived from the initials of a "very popular" magazine which covered radio extensively. However, there is no evidence of a magazine existing by this name.
It is sometimes claimed that HAM came from the first letter from the last names of three radio pioneers: Heinrich Rudolf Hertz, Edwin Armstrong, and Guglielmo Marconi. However, this cannot be the source of the term as Armstrong was an unknown college student when the term first appeared.
 Hammarlund legend
Likely an example of corporate wishful thinking, Hammarlund products were supposedly so preeminent in the pioneering era of radio that they became a part of the language of radio. As the story goes, early radio enthusiasts affectionately referred to Hammarlund products as "Ham" products, and called themselves "Ham" operators. In truth, Hammarlund was a minor and barely known company at the time "ham" started to be used.
 Sense of amateur
The term amateur in amateur radio is used to distinguish it from commercial pursuits, as radio amateurs are prohibited by law from accepting monetary or material compensation of any kind for any activities they perform as radio operators.
- Morton, Robert A (April 1909). "Wireless Interference". Electrician and Mechanic: 422–427.
- Brady, Jasper Ewing (1899). Tales of the telegraph. Doubleday & McClure Co. Retrieved February 1, 2013.
- "Reports from the Trunk Line Managers", QST, December 1916, p18.
- "Who's Who in Amateur Wireless", QST, March 1917, p30.
- http://w1af.harvard.edu/hamorigin.html, http://web.archive.org/web/20060911220039/http://mc.harvard.edu/w1af/members/w1afarticle.html, http://www.qsl.net/sars/the_origin_of_the_word_ham.htm