A psychologist wants to tell us how to “hack the happiness molecule.” The Web site Lifehacker offers tips on “how to install a laundry chute,” “make a DIY rapid-fire mouse button,” and “how to stop giving a f*ck what people think.” Online marketers desperately want to “growth hack.” The venture capitalist Paul Graham constantly talks about how tech entrepreneurs must have “hacker eyes”; his startup incubator, Y Combinator, runs an online news aggregator called Hacker News. A technology company recently recalled “a disastrous hack,” while in recent months Target, Neiman Marcus, Richard Engel, and the University of Maryland have all been “hacked.”

Clearly, “hack” is the word of the moment; its technological connotations have proliferated in both scope and presence. As used above, and in the halls of Facebook, it derives from a verb that first appeared in English around 1200, meaning to “cut with heavy blows in an irregular or random fashion,” as the Oxford English Dictionary defines it. (Another strain of the word, referring to a person—especially a writer—who does undistinguished work, comes from “hackney,” as in a horse or car for hire.)

It was at M.I.T. that “hack” first came to mean fussing with machines. The minutes of an April, 1955, meeting of the Tech Model Railroad Club state that “Mr. Eccles requests that anyone working or hacking on the electrical system turn the power off to avoid fuse blowing.” The lexicographer Jesse Sheidlower, the president of the American Dialect Society, who has been tracking the recent iterations of “hack” and “hacker” for years, told me that the earliest examples share a relatively benign sense of “working on” a tech problem in a different, presumably more creative way than what’s outlined in an instruction manual.

In the nineteen-sixties, the term seems to have migrated from the M.I.T. context to computer enthusiasts in general, and, in time, became an essential part of their lexicon. The Jargon File, a glossary for computer programmers that was launched in 1975, lists eight definitions for “hacker.” The first reads, “A person who enjoys exploring the details of programmable systems and how to stretch their capabilities, as opposed to most users, who prefer to learn only the minimum necessary.” The following six are equally approving. The eighth, and last, is “[deprecated] A malicious meddler who tries to discover sensitive information by poking around. Hence password hacker, network hacker. The correct term for this sense is cracker.”

That “[deprecated]” was a way of whistling past the graveyard, a self-conscious attempt to marginalize what later came to be called “black hat” hacking (malicious meddling), as opposed to “white hat” hacking (free-spirited creation). The black-hat sense has been around since at least November, 1963, when M.I.T.’s student newspaper, The Tech, noted, “Many telephone services have been curtailed because of so-called hackers, according to Prof. Carlton Tucker, administrator of the Institute phone system. … The hackers have accomplished such things as tying up all the tie-lines between Harvard and M.I.T., or making long-distance calls by charging them to a local radar installation.” The term subsequently migrated to computers. In 1976, a book entitled “Crime by Computer” included a chapter called “Trojan Horses, Time Bombs, Round Down, and the System Hacker.”

The black-hat sense proved irresistible to members of the media and other non-techies, no doubt in part because “hack” sounds malicious—not to mention that “hack” rhymes with “attack.” Steven Levy’s 1984 history of below-the-radar programmers and innovators, “Hackers,” was very much in agreement with the white-hat notion—its subtitle was “Heroes of the Computer Revolution”—but the book was so popular that it served as a sort of Trojan horse for the opposition. As Levy wrote in an afterword to a 1993 edition:

… the popularization of the term was a disaster. Why? The word “hacker” had acquired a specific and negative connotation. The trouble began with some well-publicized arrests of teenagers who electronically ventured into forbidden digital grounds, like government computer systems. It was understandable that the journalists covering these stories would refer to the young perps as hackers. After all, that’s what the kids called themselves. But the word quickly became synonymous with “digital trespasser.”

To give an indication of what Levy means, here are the first three uses of the word in the Times in 1990:

Computer hackers often sell the stolen codes to other students for a few dollars. Mr. Poulsen, who is charged with the most crimes, has a history as a “hacker,” who began trespassing in university and government computers as a teen-ager using the assumed name Dark Dante, according to a profile in California magazine in 1984. Mr. Morris, viewed by some as a dedicated computer researcher, by others as a reckless hacker, testified that it was never his intention to slow down computers or damage Internet data.

Although Lifehacker and other neutral or positive applications of the word are increasingly prominent, the black-hat meaning still prevails among the general public. Indeed, it has probably influenced the interpretation and enforcement of the Computer Fraud and Abuse Act. It’s as if the mere existence of the term “hacker” has added ammunition to the prosecution of such figures as Edward Snowden, Julian Assange, Chelsea Manning, and Aaron Swartz, the Internet activist who was indicted and charged with eleven violations of the act in 2011. His alleged offense was downloading many academic articles from a proprietary database; the scene of the crime, perhaps fittingly, was M.I.T.

Even as the mainstream usage of “hacker” took on its darker connotation, the geeks continued using it to mean what it always had: a righteous dude. As linguist Geoff Nunberg pointed out in a recent “Fresh Air” commentary, “Within tech culture, ‘hacker’ has become a shibboleth that identifies one as a member of the tribe.” When an M.I.T. student died in a plane crash in 1993, one of his fraternity brothers eulogized him by saying, “He was a hacker in every sense of the word, and we’re all going to miss him greatly.”

Ben Yagoda teaches journalism at the University of Delaware and is the author, most recently, of “How to Not Write Bad: The Most Common Writing Problems and the Best Ways to Avoid Them.”

Illustration by Jordan Awan.