The word "snark" is likely an amalgam of "snake" and "shark", but its description, as given in the second fit of the poem, does little to evoke either animal:

"Come, listen, my men, while I tell you again

The five unmistakable marks

By which you may know, wheresoever you go,

The warranted genuine Snarks.

"Let us take them in order. The first is the taste,

Which is meager and hollow, but crisp:

Like a coat that is rather too tight in the waist,

With a flavor of Will-o-the-wisp.

"Its habit of getting up late you'll agree

That it carries too far, when I say

That it frequently breakfasts at five-o'clock tea,

And dines on the following day.

"The third is its slowness in taking a jest.

Should you happen to venture on one,

It will sigh like a thing that is deeply distressed:

And it always looks grave at a pun.

"The fourth is its fondness for bathing-machines,

Which is constantly carries about,

And believes that they add to the beauty of scenes--

A sentiment open to doubt.

"The fifth is ambition. It next will be right

To describe each particular batch:

Distinguishing those that have feathers, and bite,

And those that have whiskers, and scratch.

"For, although common Snarks do no manner of harm,

Yet, I feel it my duty to say,

Some are Boojums--" The Bellman broke off in alarm,

For the Baker had fainted away.

In graph theory, a snark is a graph in which each vertex has three edges, but it is impossible to color the edges with only three colors so that edges of the same color don't meet at one vertex. A boojum is a planar snark. See Four-Color Theorem.

The SM-62 Snark was an intercontinental nuclear cruise missile of the US Air Force that was operational in 1960 and 1961.

In computer lingo, a "snark" is a system failure. When a user's process bombed, the operator would get the message "Help, Help, Snark in MTS!"

More generally, any kind of unexplained or threatening event on a computer is called a snark, especially those pesky entries in log files that might indicate an attempted security violation. (Also see snivitz).