Geek (gēk)
There are many historical application and mean of this word... Seems like the origin is probably German

Cambridge International Dictionary of English:

noun [C]
INFORMAL
a person who tends to be disliked because of their stupid appearance or behavior [ouch!! That sounds bad!!]

Webster:

geek n. A person who has chosen concentration rather than conformity [yeah, I like this! ]; one who pursues skill (especially technical skill) and imagination [yeap, I can handle this. ], not mainstream social acceptance [Hey, geeks can be sociable also! ]. Geeks usually have a strong case of {neophilia}. Most geeks are adept with computers and treat {hacker} as a term of respect, but not all are hackers themselves - and some who *are* in fact hackers normally call themselves geeks anyway, because they (quite properly) regard `hacker' as a label that should be bestowed by others rather than self-assumed.

One description (http://www.darkwater.com/omni/geek.html) accurately if a little breathlessly enumerates "gamers, ravers, science fiction fans, punks, perverts, programmers, nerds, subgenii, and trekkies. These are people who did not go to their high school proms, and many would be offended by the suggestion that they should have even wanted to."

Originally, a `geek' was a carnival performer who bit the heads off chickens. Before about 1990 usage of this term was rather negative. Earlier versions of this lexicon defined a `computer geek' as one who eats (computer) bugs for a living - an asocial, malodorous, pasty-faced monomaniac with all the personality of a cheese grater. This is often still the way geeks are regarded by non-geeks, but as the mainstream culture becomes more dependent on technology and technical skill mainstream attitudes have tended to shift towards grudging respect. Correspondingly, there are now `geek pride' festivals (the implied reference to `gay pride' is not accidental).

See also {propeller head}, {clustergeeking}, {geek out}, {wannabee}, {terminal junkie}, {spod}, {weenie}, {geek code}.

Merriam-Webster:

Main Entry: geek
Pronunciation: 'gEk
Function: noun
Etymology: probably from English dialect geek, geck fool, from Low German geck, from Middle Low German
Date: 1914
1 : a carnival performer often billed as a wild man whose act usually includes biting the head off a live chicken or snake
2 : a person often of an intellectual bent who is disapproved of
- geeky /'gE-kE/ adjective

NOUN: Slang 1a. A person regarded as foolish, inept, or clumsy. b. A person who is single-minded or accomplished in scientific or technical pursuits but is felt to be socially inept. 2. A carnival performer whose show consists of bizarre acts, such as biting the head off a live chicken.
ETYMOLOGY: Perhaps alteration of dialectal geck, fool, from Low German gek, from Middle Low German.
OTHER FORMS: geeky - ADJECTIVE

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.