What is the definition or description of: head trauma?

Head injury: Any injury to the face, skull, or brain as a result of blunt force, or penetrating trauma. It can also occur due to rapid acceleration or deceleration forces.

Nonspecific: Any kind of head injury could be included. Closed head trauma can involve a minor bump, a bruise (goose-egg), a concussion or even a traumatic brain injury. There could be intracranial bleeding, or skull fracture. So, long and short, the term is not very meaningful, and unlikely to be useful in describing an event.