Concussion, n.
Etymology: [L. concussio, fr. concutere, concussum, to shake violenty; con- + quatere to shake. See Cashier, Quash.]
1. A shaking or agitation; a shock; caused by the collision of two bodies. It is believed that great ringing of bells, in populous cities, hath dissipated pestilent air; which may be from the concussion of the air. Bacon.
2. (Med.)
A condition of lowered functional activity, without visible structural change, produced in an organ by a shock, as by fall or blow; as, a concussion of the brain.
3. (Civil Law)
2 more senses
The unlawful forcing of another by threats of violence to yield up something of value. Then concussion, rapine, pilleries, Their catalogue of accusations fill. Daniel. Concussion fuse (Mil.), one that is ignited by the concussion of the shell when it strikes.
Syn. -- See Shock.
Shades of meaning
Fernald has no entry of its own for concussion; he lists it under blow, collision.
Where he writes about it:
Concussion is often by transmitted force rather than by direct impact; two railway-trains come into collision; an explosion of dynamite shatters neighboring windows by concussion. — from collision