Whereas geeks bite the heads off chickens; pretty clear who got the short end of THAT stick.

Working off definition number THREE, however, I personally distinguish between geeks as enthusiasts and nerds as knowledgeable. Computer geeks use and enjoy computers a lot but may know little about them; computer nerds can build and recite detailed histories of them. A nerd may thus also be a geek (and usually is, though occasionally people become very knowledgeable about subjects in which they have little personal interest,) but a geek is not necessarily a nerd. Note: My personal usage of a given word does not necessarily correspond to the accepted or defined usage.