The Twitter account of the Merriam-Webster dictionary also posted a quick guide on the difference between "pour-over" ("to make expensive coffee"), to "pore over" ("to read or study carefully") and, as an added jab at the president, a "comb-over".
On Tuesday Trump defended his tweeting style on Twitter admitting that he took pride in his writing ability. "I capitalize certain words only for emphasis, not b/c they should be capitalized!".
This isn't the first time that Rowling has made fun of Trump on social media.
Her hilarity was prompted by a tweet the USA president posted attacking "Fake News" and explaining his idiosyncratic use of capital letters.
Immediately deleting the tweet and replacing it with a version using the correct choice of word was not good enough for some critics, however, including author JK Rowling.
The bestselling Harry Potter author, who has sold over 500 million books across the world, was so amused by Mr Trump's error she filled her Twitter feed with laughter - writing "hahaha" for lines on end.
POTUS got trolled hard by actual best selling author, J.K. Rowling; various other celebrities; the dictionary and many other English-speakers. He misspells "pore" in the tweet.
A less noticed mistake that some users also pointed out in Trump's tweet was that he should have used a hyphen in the term "best selling" when he made reference to the books he's written. "Ghostwriters on all of them".