Gnarl

gnarl n. extreme technical sections. Characterized by very rough, rooty, slippery, or rocky sections. Commonly found in the Pacific Northwest and New England. "He has got some great bike handling skills and can really scream through the gnarl."

From the Dictionary of Mountain Bike Slang

Gnarl! is also the title of a collection of short stories written by Rudy Rucker occasionally with the help of other cyberpunk/SciFi authors including Bruce Sterling, Paul Di Filippo, and Marc Laidlaw. Gnarl! is the companion collection to Seek!, a collection of Rucker's short nonfiction.(He is a mathematician and computer science professor as well as a writer.) The titles come from his odd motto: Seek Ye The Gnarl!

As an die hard fan of Rucker I fully recommend these collections, but must warn that Gnarl! includes all his short stories from 1976 to 1999, Good and Bad. If you aren't a fan of Rucker already you may want to start with Software, or one of his other novels.

Gnarl (?), v. i. [imp. & p. p. Gnarled (?); p. pr. & vb. n. Gnarling.] [From older gnar, prob. of imitative origin; cf. G. knarren, knurren. D. knorren, Sw. knorra, Dan. knurre.]

To growl; to snarl.

And wolves are gnarling who shall gnaw thee first. Shak.

© Webster 1913.

Gnarl, n. [See Gnar, n.]

a knot in wood; a large or hard knot, or a protuberance with twisted grain, on a tree.

© Webster 1913.