Obfuscation
Obfuscation means making something harder to understand, usually by complicating sentences. Weasel words are a form of obfuscation. Obfuscation is usually used when people either do not know what they are talking about or wish to hide what they really mean.
Some people say that when doctors use difficult medical words to hide unpleasant things from patients, they are using obfuscation.
Technical term: Obfuscation is sometimes used to make source code much harder to read and reverse engineer. This can be a significant problem for technology like Python and JavaScript that require source code to be exposed in order to function.