incoherent

Incoherent describes something written or spoken that is not sticking together, is rambling or is not expressed in an orderly way. (adjective)

An example of incoherent is an essay that changes positions halfway through.
An example of incoherent is a person who talks nonsense and makes no sense.
An example of incoherent is something written or said by a person who has only a very limited grasp of the language in which he is speaking.

See incoherent in Webster's New World College Dictionary