With a simple name change, Elon Musk has created confusion in social media.

The bewilderment stems from Mr. Musk’s move last month to rebrand Twitter, which he owns, as X. No major social media app has undergone such a name change before, at least while it had tens of millions of active users.

In 2016, Snapchat dropped “chat” from its corporate name, but kept the app’s name unchanged. When Facebook changed its parent company name to Meta in 2021, it also left the name of its flagship social network alone.

The rebranding has been hair-raising for Twitter fans, who embraced the company’s iconic blue-and-white bird logo and used a bird-related lexicon when talking about the platform. A tweet referred to a post; tweeting was a verb for posting, and sharing another person’s post was known as retweeting.

Some people have wondered if the X name will stick, especially with the word tweets still appearing on the site. The app’s home button is also still shaped like a birdhouse, and the company’s website — at least for now — remains Twitter.com.

So is the Twitter name retired? And do we now call a tweet a “xeet” or “xcerpt”?

Really, what do we call Twitter now?

Sorry, die-hard Twitter fans, it’s X.

X said its app would definitively be called X going forward. In marketing copy, the company declared, “The X app is the trusted digital town square for everyone.” The app has a new slogan, too: “Blaze your glory!” (Twitter’s previous tag lines included “Let’s talk” and “It’s what’s happening.”)

The Associated Press also updated its stylebook, which many regard as the gold standard, to reflect the name change. It suggested that media outlets call the company and its social media platform “X, formerly known as Twitter.”

Mr. Musk had laid the groundwork for the name change for some time. When he bought Twitter last year, he formed a new parent company, X Corp., for the transaction.

In other words, people are now using X, an app by X Corp.

Mr. Musk is slowly purging Twitter’s brand digitally and physically. While Twitter.com still sends users to the service’s familiar home page, so does X.com, indicating that the website could soon change. The bird branding that adorned the website and the app has been eradicated.

Mr. Musk also briefly erected a light-up X sign atop the company’s San Francisco’s headquarters last week. (It was removed this week after a permit dispute.) And he replaced the bird-themed names of conference rooms at X’s offices with X-themed names including “eXposure,” “eXult” and “s3Xy,” and ordered the removal of bird logos around the building.

What do we call tweets?

Tweets are now posts. In the same app update that wiped out the bird logo, the company swapped its classic blue “tweet” button for one that says “post.”

Some users have proposed other names for posts. One suggestion has been “xeets” (pronounced zeets), an X-themed play on tweets. Others suggested “xcerpts.” None of these terms seem to have caught on in a big way, at least so far.

Some of the app’s other monikers may also change. Retweets are likely to become reposts, while quote tweets — which refer to retweets that add one’s own commentary — may just become comments or quote posts.

Why did this change happen?

Mr. Musk has long been enamored with creating a company called X. In 1999, he started X.com, an online bank that later merged with the electronic payments service PayPal. Nearly two decades later, he bought the X.com website back from PayPal.

Mr. Musk has said he envisions X as an “everything app” that will allow users to share social media posts, order dinner and transfer money. Taking over Twitter was just the first step, he said.

“X is the future state of unlimited interactivity — centered in audio, video, messaging, payments/banking — creating a global marketplace for ideas, goods, services, and opportunities,” Linda Yaccarino, the company’s chief executive, posted last month.

What happens if I can’t shake off the Twitter name?

We get it! It will take time to adjust colloquially to X. The Twitter name and its bird-related vocabulary have been used since 2006 and were embedded in popular culture.

The change may be especially difficult since “it is extremely rare for consumers to develop a lexicon around a brand,” said Mike Proulx, a vice president and research director at Forrester. “It would be viewed as an advantage in most circumstances because it suggests a deepening of the brand-consumer relationship.”

Now Mr. Musk has to create that relationship with the X brand, even as some users insist they will stick to the old terminology.

“A lot of people are confused about what to do now that Twitter has been officially rebranded as X, and I thought I’d write up a helpful guide for those of you struggling with change,” one user recently wrote. “You keep calling it Twitter and pretend you do not see it!”