Syncope

This is the official medical term for fainting or sudden loss of consciousness. “Pre-syncope” is the feeling that you’re about to faint.

The most common form is “vasovagal syncope” which means you have a sudden drop in blood pressure which causes you to faint due to lack of oxygen to the brain, so-named because the vagus nerve regulates heart rate (among other things).

It’s pronounced “SINK-o-pee.”

Why I Looked It Up

In The Mystery of Dr. Fu-Manchu:

“Suoutherly died during the night, but Sir Frank Narcombe, arriving a few minutes later, unhesitatingly pronounced death to be due to syncope, and seems to have noticed nothing suspicious.”

You can’t die directly from fainting, so perhaps it was assumed he hit his head on something when he fell?