From www.dictionary.com :
Our Living Language Our word geek is now chiefly associated with student and computer slang; one probably thinks first of a computer geek. In origin, however, it is one of the words American English borrowed from the vocabulary of the circus, which was a much more significant source of entertainment in the United States in the 19th and early 20th century than it is now. Large numbers of traveling circuses left a cultural legacy in various and sometimes unexpected ways. For example, Superman and other comic book superheroes owe much of their look to circus acrobats, who were similarly costumed in capes and tights. The circus sideshow is the source of the word geek, a performer who engaged in bizarre acts, such as biting the head off a live chicken. We also owe the word ballyhoo to the circus; its ultimate origin is unknown, but in the late 1800s it referred to a flamboyant free musical performance conducted outside a circus with the goal of luring customers to buy tickets to the inside shows. Other words and expressions with circus origins include bandwagon (coined by P.T. Barnum in 1855) and Siamese twin."
Word History: The word nerd, undefined but illustrated, first appeared in 1950 in Dr. Seuss’s If I Ran the Zoo: And then, just to show them, I’ll sail to Ka-Troo And Bring Back an It-Kutch a Preep and a Proo A Nerkle a Nerd and a Seersucker, too! (The nerd is a small humanoid creature looking comically angry, like a thin, cross Chester A. Arthur.) Nerd next appears, with a gloss, in the February 10, 1957, issue of the Glasgow, Scotland, Sunday Mail in a regular column entitled ABC for SQUARES: Nerda square, any explanation needed? Many of the terms defined in this ABC are unmistakable Americanisms, such as hep, ick, and jazzy, as is the gloss square, the current meaning of nerd. The third appearance of nerd in print is back in the United States in 1970 in Current Slang: Nurd [sic], someone with objectionable habits or traits… An uninteresting person, a dud. Authorities disagree on whether the two nerdsDr. Seuss’s small creature and the teenage slang term in the Glasgow Sunday Mailare the same word. Some experts claim there is no semantic connection and the identity of the words is fortuitous. Others maintain that Dr. Seuss is the true originator of nerd and that the word nerd (comically unpleasant creature) was picked up by the five- and six-year-olds of 1950 and passed on to their older siblings, who by 1957, as teenagers, had restricted and specified the meaning to the most comically obnoxious creature of their own class, a square."
Just for your info…