It may have been a simple keyboard slip, or a "senior moment"; the soon to be 71-year-old Trump's huge catalog of Twitter bloopers regularly offer evidence that a spelling- challenged speed-tweeter occupies the Oval Office.
It also shows that four months into his administration, the US president's unfiltered use of the medium remains unchecked.
The consequence is deep turmoil in his communications staff: the White House is rife with rumors that the boss is preparing mass firings, and this week, communications director Mike Dubke resigned just four months into the job.
That's what happened after his nonsensical tweet in the early hours of Wednesday: "Despite the constant negative press covfefe."
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The word doesn't exist in English, or apparently any human language. Mock interpretations said it was Russian for "I resign," ancient Egyptian for "media witch hunt," or more unprintable things.
The Regent's English Language Center in London wrote: "We can confirm that 'covfefe' is not an English word. Yet."
Trump -- who declared during the election campaign last year that "I'm very highly educated. I know words; I have the best words" -- even jumped into the fun.
After deleting the original tweet, he put out a new one: "Who can figure out the true meaning of 'covfefe' ??? Enjoy!"
Pressed later on the issue, White House spokesman Sean Spicer held tight to the "secret," quipping: "The president and a small group of people know exactly what he meant."
But coming amid reports Trump will pull the United States out of a global climate deal, the "covfefe" phenomenon illustrated how his Twitter habit can divert attention from his policy agenda.
The White House team has repeatedly fallen prey to embarrassing errors -- a list of global attacks released in February included "Denmakr" (Denmark) and "San Bernadino" (San Bernardino).
When British Prime Minister Theresa May visited Washington, the presidential and vice-presidential agenda both spoke about "Teresa," and Australian Prime Minister Malcolm Turnbull was referred to as the president of his country.
For reporters as well as observers, these mistakes are symptomatic of the collective lack of experience and discipline in the White House.
The communications team appears to have given up. Rather than try to spin Trump's sometimes contradictory views, they have turned to just praising the president and repeating what he says.
In early May, Spicer -- whose job is believed to be in the balance -- began responding to journalists' questions by saying things like "The tweet speaks for itself. I'm moving on."
And rather than try to interpret Trump's controversial remarks in Riyadh, Jerusalem, Brussels and Sicily last week, White House aides took to simply lauding his first trip abroad as "extraordinary" and "historic."