He spoke almost incoherently, as if he'd lost his *d. In a way, he had.
People may speak incoherently or even make up words.
In some scenes, he appears to slur his words or speak incoherently.
Suddenly the navigator began speaking so fast and incoherently, that Bykov could only understand isolated words.
He at times spoke incoherently in both English and Spanish, they said.
The whole house was roused; for she was there, in a moment, very pale too, and speaking incoherently.
She was sitting on a small sofa, speaking incoherently to herself.
By the time the duke returned home, he was speaking incoherently, and had become ill.
Another man was brought over, shaking, and speaking incoherently.
At times, the men sat up and spoke incoherently.