What does concussion mean?
Concussion is a noun referring primarily to a mild traumatic brain injury caused by a blow, bump, or jolt to the head that temporarily disrupts normal brain function. Typical symptoms include headache, dizziness, nausea, blurred vision, confusion, and difficulty remembering the event itself. Because a person need not lose consciousness to sustain one, concussions frequently go unrecognized, a fact that has driven growing public awareness and strict return-to-play protocols in professional and amateur sport alike. The word also retains an older, broader sense: any violent shaking or jarring impact, such as the concussion of an explosion. Derived from Latin roots meaning "to shake violently," it entered English in the fifteenth century but gained its dominant medical meaning later. Today the word appears constantly in news coverage of football, rugby, hockey, and military contexts, and its prominence reflects society's sharpened understanding that even seemingly minor head injuries deserve careful attention and adequate recovery time.
A mild traumatic brain injury resulting from a blow or jolt to the head, causing temporary impairment of brain function such as headache, dizziness, and memory disturbance.
"She wore a helmet on every ride after her concussion the previous winter."
Often treated as uncountable in British medical usage ("he suffered concussion") but commonly countable elsewhere ("he suffered a concussion").
A violent shaking or jarring impact, especially one produced by an explosion or heavy collision.
"The concussion of the blast rattled windows across the valley."
This older, general sense now appears chiefly in formal or technical descriptions of explosions and impacts.
The plural refers either to multiple instances of head injury (e.g., across different people or repeated injuries) or, rarely, multiple instances of violent impact.
"Repeated concussions can have lasting effects on cognitive health."
You don't have to be knocked unconscious to have a concussion — most concussions happen with no loss of consciousness at all, which is exactly why they so often go undiagnosed.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of concussion
Concussion comes from the Latin concutere, meaning "to shake violently," formed from com- (an intensifying prefix) plus quatere ("to shake"). The noun form concussio passed into English via Middle French in the late Middle Ages, with the word attested by the fifteenth century. Its original sense was the general one — a violent shaking or impact — while the specific medical sense of a brain injury became established later, solidifying in medical writing over subsequent centuries. It shares its root with percussion, repercussion, and discuss, all ultimately descended from quatere.
Related word forms
How concussion is actually used
"Concussion" is used almost exclusively as an uncountable noun in medical contexts — one says "she suffered concussion" rather than "a concussion," though "a concussion" is equally standard in general American usage. It carries a serious, clinical connotation and is strongly associated with sports medicine and head-injury awareness. The older, general sense of a violent shaking or impact (as of an explosion) survives mainly in formal or technical writing.
Easily confused with concussion
A contusion is a bruise (injury without broken skin), whereas a concussion is specifically a brain injury from a jolt or blow to the head.
Discussion means conversation or debate; it shares a Latin root with concussion but has an entirely unrelated modern meaning.