"Plus" is a positive workhorse of a word. It can be a preposition (two plus two), an adjective (a C-plus grade), or a noun (the good weather is a plus). It has stood for the mathematical function of addition since the 1660s, and has been accepted as a conjunction — as in "beauty plus brains" — since the 1960s.  It can help define a merchandise category (plus-size), signify a partner (plus one), or identify a revved-up product (Alka Seltzer Plus).

Until recently, though, "plus" has mostly stayed out of the verb column. That's changing, on the evidence of some recent sightings.

Consider the current marketing campaign for Sutter Health, a large network of doctors and hospitals in the San Francisco Bay Area. The campaign tagline is "We Plus You," and it isn't meant as an equation. Rather, it's a subject-verb-object sentence, as in "We plus you! We really, really plus you!"

"At Sutter Health, we believe in partnering with you," says the voiceover. "Because you plus us ... and we plus you." Translation: We make each other's lives better.

Enterprise Rent-A-Car is also positive about plussing — although "Plus Your Life," the slogan for the "enhanced Enterprise Plus loyalty program," is ambiguous.

The phrase makes marketing sense only if we understand "plus" to be a verb meaning "improve." At first glance, though, it's easy to think it means "And your life." That was Washington Post copy editor and usage-guide author Bill Walsh's mocking interpretation: he tweeted a photo of one of the "Plus Your Life" ads and commented, "If you're willing to die for Enterprise Rent-A-Car."

To plus began cropping up in social-media circles a couple of years ago, when Google launched its Google Plus service. To give a stamp of approval to something on Google Plus, you click a "+1" icon. As Ben Zimmer wrote in a 2011 Word Routes column, Google recommended calling this action "+1'ing." But users started referring to it as "plussing."

But it turns out Walt Disney got there first, some 70 years ago. According to How to Be Like Walt: Capturing the Disney Magic Every Day of Your Life, a chatty/motivational 2004 biography that refers to its subject by his first name, Disney emphasized "the plus factor" to his artists and designers:

Sometime during the 1940s, Walt coined the term "plussing." Normally, the word "plus" is a conjunction, as in "two plus two equals four." But Walt used the word as a verb — an action word. To "plus" something is to improve it. "Plussing" means giving your customers more than they paid for, more than they expect, more than you have to give them. ... He began by plussing Mickey Mouse with sound, then plussing the Silly Symphonies with color. Walt plussed the skills of his artists by sending them to art school at his own expense. Walt's relentless quest for excellence kept him at the leading edge of his industry — and left his competitors, well, nonplussed.

(For more discussion of nonplussed, see here and here.)

The film studio Pixar is a Disney subsidiary, so you might expect to find "plussing" there, too. And you'd be right — except that Pixar's "plussing" is different from Disney's. A recent New York Times article about giving constructive feedback to employees described Pixar's "plussing" as "using words like 'and' and 'what if' rather than 'but'" as a way to "build and improve on ideas without using judgmental language." Interestingly, even within Pixar that definition is relatively new: a 2006 article about the company referred to "a combined effort to make their projects the best they can be, something they refer to as 'plussing'." In other words, Pixar inherited "plussing" in the Disney sense and modified it for a different context.

The push to plus comes from another direction, too: government. Here's a passage from a March 21 news article in the New York Times:

"They are plussing up their assistance," said Robert S. Ford, the American ambassador to Syria, referring to Iran. "They are plussing up their people on the ground. They are plussing up what they [sic] sending in."

Lest you label Ambassador Ford a language pioneer, take a look at the Congressional Record for June 20, 2000, in which Rep. Bob Filner of California takes the floor to speak about the budget for space research:

We should be plussing-up the account in research, as an amendment I had on the floor to do. We should be plussing-up the account for the State veterans homes, which I have an amendment to do, without having to take from NASA.

What's up with "plus-up"? Well, it turns out to be a term of art in governmental budget negotiations. A "plus-up" is money not part of the president's budget request, according to a 2006 news article cited in Grant Barrett's Double-Tongued Dictionary. From the noun form it was doubtless an easy and logical slide into verbification.

By now, "plussing" seems to be part of the lexicon, for plus or minus. After all, writes language maven Ben Yagoda in When You Catch an Adjective, Kill It, the plus symbol is already "a favorite of instant messagers, note takers, hip-hop songwriters, conglomerates (Gulf + Western), and people demonstrating eternal love by carving their initials into trees." With such a dynamic résumé, why not recognize "plus" as the verb it clearly yearns to be?

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Nancy Friedman is the chief wordworker at verbal-branding consultancy Wordworking, and the author of a fine blog on naming, branding and more called Fritinancy. Nancy has named a venture-capital firm, a laser hair-removal device, a mobile-money service, and many other companies and products. A former journalist, she still writes or ghostwrites articles, speeches, white papers, and books. Click here to read more articles by Nancy Friedman.