Definition of "concussion"

concussion

/kənˈkʌʃən/

noun
countable and uncountable, plural concussions
1. A violent collision or shock.
  Quotations
  It is believed that great ringing of bells, in populous cities, hath dissipated pestilent air; which may be from the concussion of the air.
  1631, Francis [Bacon], “(please specify |century=I to X)”, in Sylua Syluarum: Or A Naturall Historie. In Ten Centuries. […], 3rd edition, London: […] William Rawley; [p]rinted by J[ohn] H[aviland] for William Lee […]
  [Water vapour bubbles] hit againſt the ſides of the more eminent and Mountainous Places, of the Globe, and by this Concuſſion are condenſed, and thus become heavier than the Air they ſvvom in, and ſo gleet dovvn the rocky Caverns of theſe Mountains, […]
  1705, George Cheyne, “Of the Existence of a Deity”, in Philosophical Principles of Natural Religion: […], London: […] George Strahan […], § XXIX, page 184
2. (uncountable in Commonwealth, countable in Canada, US) An injury to part of the body, most especially the brain, caused by a violent blow, followed by loss of function.
3. (obsolete, law, civil law) The unlawful forcing of another by threats of violence to yield up something of value.
  Quotations
  Then Concussion, Rapine, Pillories, / Their Catalogue of Accusations fill.
  1595, Samuel Daniel, “(please specify the folio number)”, in The First Fowre Bookes of the Ciuile Wars between the Two Houses of Lancaster and Yorke, London: […] P[eter] Short for Simon Waterson