Inquiring minds want to know: "Fetching," a reader writes, "seems to be used mostly to refer to female outfits. I cannot think of when I have heard it used with regard to males. Don't know how this relates to Jack and Jill.... My wife wants to know whether it is the male or female that is being fetched."
To cut to the chase: It's the male, if you understand the underlying metaphor of the idiom.
The Online Etymology Dictionary gives quite a roster of meanings for the Old English verb that led to the modern fetch: "to fetch, bring near, obtain; induce; to marry." A fairly broad job description, don't you think?
Today, fetch refers, among other things, to what puppies do to sticks, and what paintings do to prices, especially high ones, at art auctions. A recent Associated Press piece on dog art (paintings of, not by, dogs, that is) captured both senses at once. It began, "Dogs seem to be as popular on a canvas these days as they are on a leash, with paintings of dogs drawing big bucks and big crowds," and ran under the headline "Paintings of dogs fetch prices to bark at" – to bark at, not sneeze at, was evidently the idea.
Fetching is also what Jack and Jill did, or sought to do, to a pail of water. (The nursery rhyme is unclear as to whether the pair actually accomplished their mission. Jack's fall and Jill's unexplained "tumbling after" cast doubt on whether the pair, whoever they were, were really up to the job. One theory holds that Jack and Jill represent Louis XVI and Marie Antoinette of France, deposed and beheaded in 1793 – a theory "made difficult," Wikipedia notes, "by the fact that the earliest printing of the rhyme pre-dates these events." But I digress.)
Fetching, the participial adjective, has a different track. Again, to cite the Online Etymology Dictionary: By the 1580s, fetching had a sense of "crafty," or "scheming." This seems related to fetching in the sense of "inducing" someone to do something. Three centuries later, fetching had come to mean "alluring" or "fascinating." That sense comes into play when a woman's outfit, or perhaps her hat or coiffure, is described as "fetching."
The synonyms the American Heritage Dictionary offers up in its thesaurus entry for fetching include not only the unisex "attractive" and "engaging" but also "bewitching," "enchanting," "enticing," and even "tempting." So the metaphor is that of a spell-casting female.
In addition to the category of "words with curious metaphor built in," fetching also fits into "words whose job descriptions have narrowed." It's used for clothing, hats, and hairstyles, and that's about it. You wouldn't use it for a chocolate mousse, however "enticing" it may be.
Other words have gotten themselves into even tighter corners. When does specious appear but in the company of "argument"? Arrant looks, from the dictionary, like a useful word to mean "complete" or "extreme"; but it travels largely in the company of either nonsense or idiocy.
Woeful gets paired with "ignorance" or "lack," except when sportswriters use it to bewail the performance of a losing team ("Woeful Leafs go goalless again"). The adverb woefully pairs with "inadequate" so often that the two make a set phrase. Like that Old English word that became today's fetch, these words have seen their job descriptions shrink.