Incoherent (adjective)

1. Not able to speak or express oneself clearly and effectively.
2. Not logically consistent or orderly.
3. Not able to be understood easily or clearly.
4. Not having a clear and consistent structure or organization.

Origin:

From latin incoherentem, accusative singular of incoherent, from in- ("not") + cohaerens ("coherent").

Examples:

1. The patient's speech was incoherent.
2. His thoughts were incoherent.
3. The essay was incoherent and hard to follow.
4. The argument was incoherent and lacked logical structure.
5. The plan was incoherent and failed to address all the necessary points.