What is the difference between の意味は何 and はどういう意味? When asking for the definition of a word, I've been told to use the latter, but I don't know why the former is incorrect.
Use the latter if you want to speak and write "natural" Japanese. 「～～はどういう意味ですか。」 is how native speakers ask for a word's definition.
「～～の意味はなんですか。」, while grammatical, sounds SO "directly translated" from "What is the meaning of ~~?". It is not very natural, if not incorrect.