Doctor John Dolittle is the main character of children's books (Dr. Dolittle) written by English writer Hugh Lofting in 1920.
Why did he choose Dolittle as the surname of the character? Is it related to the word "little" which means small?
The word "little" doesn't only mean physically small; it can also mean, more generally, the opposite of "lots". Thus, the name "do little" seems to indicate somebody lazy who doesn't do much.
This is consistent with the way the character is portrayed: from the outside, or to people who don't know him, he may seem like a silly or idle person who doesn't take care of himself or his life. This is a theme of the early chapters of the book, when he slowly loses his money and possessions due to caring more about his animals than about the opinion of high society, until other people in the town jeer at him while the animals and children still like him as before. Even Tommy Stubbins in The Voyages of Doctor Dolittle is surprised when he first meets him, because his outer appearance is not at all what he expected:
“Surely,” I thought, “this cannot be the great Doctor Dolittle himself!”
I suppose after hearing so much about him I had expected some one very tall and strong and marvelous. It was hard to believe that this funny little man with the kind smiling face could be really he.
In the same way that a name isn't the best way to judge a person, neither is their outward appearance. Perhaps, by giving him the name Dolittle, the author ensured that any superficial way of assessing him would give a negative impression: his name suggests someone lazy, while his lifestyle takes no heed of money or the opinions of his peers. He will only be liked by those who look deeper to see his kindness and true self.
(The significance of the name may be hinted at in the very first introduction we get to the character in The Story of Doctor Dolittle. In this version, there is a sentence "Despite his name, laziness was not in his nature." But I'm not sure of the provenance of this quote, as it's not included in the Project Gutenberg or Wikisource versions of the text, or any other version I could find online. I also seem to remember, when I read the books as a child, some joke about changing his name to Doalot. But either that's also in another version, or perhaps a completely different story that also had a character called Dolittle, because it's not in the texts I could find online either.)