Often seen as V. S., etc. Gunshot wound to the head, arm, head, through the thighs, etc.
My Italian son-in-law states the latin term meaning something like a sucking sound. I've forgotten the exact translation.
A Goggle search "Civil War Medical Terminology" will get you there. See: http://freepages.genealogy.rootsweb.ancestry.com/~grundyconnections/medterm.html