Nowadays the word geek is a slang term originally used to
describe odd or non-mainstream people, with different connotations ranging from
"an expert or enthusiast" to "a person heavily interested in a
hobby", with a general pejorative meaning of "a peculiar or otherwise
socially inept person, especially one who is perceived to be overly
intellectual".
Although often considered as a pejorative, the term is also
often used self-referentially without malice or as a source of pride. Its
meaning has evolved to connote "someone who is interested in a subject
(usually intellectual or complex) for its own sake."
But in the early 20th Century a geek was a circus
freak and geekery meant bizarre physical acts performed by geeks. Amongst these were carnival performers, often
billed as wild men, whose act usually included biting the head off a live
chicken or snake. Gross!
The meaning changed to its more expert / eccentric one after
Robert Heinlein used the term geek to mean a maths freak in 1952.
