The word Obtunded is not used in everyday conversation. Its meaning is; mentally dulled. A person may be obtunded due to head trauma. Yet, you can understand why it might be commonly used, among certain medical persons.
Even less used is obtundation, which means, a dulled or reduced level of alertness or consciousness. One might report, that "Mr. X is in a profound state of obtundation." One of the ways to determine if the person is arousable, is to rub their sternum briskly and firmly, with your knuckles. Yes, it cause a noxious pain. Early in my career I worked with a nurse named Jan, whose sternal rub was legendary. Numerous obtunded persons, came to wakefulness under her forceful rub.

The Obtundation Rap

The shift was OK
Until he tried to spoil it,
Circling the
Obtundation toilet.

I lit up his pupils
And screamed, "Look here, Bub",
I'm known far and wide
For my killer sternal-rub,
You might think you can fool me
But as your nurse, I get first dibs,
To rap out the death-march
On your skinny little ribs.

Your brand of behavior
Will not be endured,
One way or another
Your obtundation will be cured.

Fibril_late; 1992