“This word is revolting and must be purged,” wrote Greg Baumann in the Silicon Valley Business Journal several years ago, in a roundup of “the most loathsome business words in 2014.” The offending jargon? “Influencer.”

“It’s fine as applied to people who actually wield influence,” Mr. Baumann complained. “However it has spawned a wannabe army of self-appointed experts who pen too-often insipid business how-tos. Can anything be done about this?”

Bad news: fast forward to 2020, influencers are everywhere. On the professional networking site LinkedIn, a search turns up nearly 70,000 profiles with the word “influencer.” (LinkedIn is a primary culprit in propagating the term. Since 2012, its “Influencers” program has shared posts from such industry leaders as Richard Branson, Bill Gates and Arianna Huffington.)

The situation is even more dire on social media sites like Twitter and Instagram, which are full of lifestyle, fashion and beauty influencers, often joining with brands for “influencer marketing” opportunities. And as The Wall Street Journal recently reported, even stylish dogs can now be social media influencers, or “dogfluencers,” for short.

The influence of “influence,” from Latin roots meaning “flowing in,” goes back to medieval astrological thinking. Heavenly bodies were believed to emit an invisible fluid that would affect the fate of humans, streaming into their bodies. Chaucer wrote of the ethereal substance in “Troilus and Criseyde”: “O influences of these heavens high.”

The word eventually got transferred to the invisible power that could be wielded over people in the material world. “Influence” often shows up in Jane Austen novels, as in “Emma,” when the title character wonders of her beloved Mr. Knightley, “When had his influence, such influence begun?”

Influence found a more psychological footing with Harry A. Overstreet’s 1925 “Influencing Human Behavior.” Overstreet’s findings were put into practical use in Dale Carnegie’s 1936 self-help classic, “How to Win Friends and Influence People.”

Modern techniques of “influencer marketing” owe a debt to the sociologists Paul Lazarsfeld and Elihu Katz, whose 1955 book “Personal Influence” laid out the “two-step flow” model of mass communication, with information flowing first to opinion leaders before spreading out to the populace at large.

The influence of opinion leaders in the digital era can be carefully quantified in terms of their “reach” or following. As early as 2003, at an event sponsored by Procter & Gamble called Buzzpoint, marketers shared ways of getting their message out to key influencers.

While prominent bloggers were the original online influencers, the rise of social media has allowed just about anyone with a healthy number of followers to assume the mantle. On the visual bookmarking site Pinterest, top users are called, naturally, “Pinfluencers.”

The techie obsession with influence and “thought leadership” is certainly ripe for ridicule. As the Twitter parody account @ProfJeffJarvis, a spoof of real-life media pundit Jeff Jarvis, memorably proclaimed, “We are now in the post-thinker era. This new age belongs to a different group: the thinkfluencers.”