expressed in a way that is not clear
incoherent - unclear
Something ‘incoherent’, whether it be text or speech, lacks clarity and orderly arrangement or relevance. That makes it very difficult to understand or follow. Most commonly this is due to a lack of preparation, nerves, or some form of intoxication. Can lead to confusion and difficulties, particularly in a professional environment. The opposite is also true - if something is 'coherent', it is clear and easy to understand.
The presentation Chris gave was a jumbled, incoherent mess. I had no idea what point he was trying to get across.
The doctor couldn’t understand what was wrong with the drunken patient because he was babbling incoherently.
Despite having months to work on her assignment, the incoherence of the student’s argument showed that she had not done the required reading.