In a tweet criticising his Democratic rival Hillary Clinton, Trump wrote: "Hillary Clinton should not be given national security briefings in that she is a lose cannon with extraordinarily bad judgement & insticts."
Trump's tweet echoed a statement made by Clinton in May, when she called him an "unqualified loose cannon", the Independent cited CBS News report.
However, Twitter users were quick to point out the three spelling mistakes in his short tweet: "lose" instead of "loose", "insticts" instead of "instincts", and "judgement" instead of the correct US spelling of the word, "judgment".
"There is no scenario to ever exist where you have not been the loosest cannon in the room," the Independent quoted well-known model Christine Teigen as saying in a tweet.
This is not the first time Trump has misspelled words or made typos on the social network.
"Every poll said I won the debate last night. Great honer!" he wrote in February, in a tweet that has since been deleted after people pointed out the correct American spelling was "honor".
He also once spelled the word "choker" in two different ways within the same tweet, also in February: "Lightweight Marco Rubio was working hard last night. The problem is, he is a choker, and one a choker, always a hocker! Mr. Meltdown."
And at a rally in Knoxville, Tennessee last November, the poster on his podium had misspelled the state, using only one "s".
Former Republican President George W. Bush was also known for his gaffes and verbal slip-ups, sometimes known as "bushisms", the Independent reported.
According to Slate, in 1999 Bush said, "The important question is, how many hands have I shaked?"
And in 2000, he said in Florence, South Carolina: "Rarely is the question asked: Is our children learning?"