Im not sure that you can measure intelligence by the words one chooses to use. When i hear the word Rocketman, it reminds me of a song with that title. When i hear the word Dotard, im lost. Why? Because i dont know what Dotard means.
"Dotard" is a combination of Donald and retard. I do believe that one can detect a level of intellect by the words they choose. Trump has a limited vocabulary. The most recent example I can think of is his comment about the devastation in Puerto Rico. Paraphrasing, he said, "Puerto Rico is in very, very, very bad shape." Someone else might have said, "Puerto Rico has suffered extreme devastation." He likes little words and uses them repetitively. Then again, when he speaks, he speaks to his base, which probably doesn't understand words with more than two syllables.
Say what you will about the Pillsbury Doughboy, he gave Cheeto Benito a real taste of his own medicine with the name "Dotard." But don't forget, Dotard does know more about ISIS than the generals.
When Dotard dies, researchers are gonna open up his head and...... pfft, was gonna say something about his brain but the head will probably be completely empty.
I've asked a couple of questions regarding Trump/Dotard and given the definition which I am happy to do for you again. "A person, esp. an old person exhibiting a decline in mental faculties; a weak-minded or foolish old person"