VERB (2)

1. shake violently;

2. injure the brain; sustain a concussion;

The Collaborative International Dictionary of English v.0.48:

Concuss \Con*cuss"\, v. t. [L. concussus, p. p. of concutere.
   See Concussion.]
   1. To shake or agitate. "Concussed with uncertainty."
      --Daniel.
      [1913 Webster]

   2. (Law) To force (a person) to do something, or give up
      something, by intimidation; to coerce. --Wharton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

concuss
    v 1: shake violently
    2: injure the brain; sustain a concussion