WordNet (r) 3.0 (2006):

misbehaviour
    n 1: improper or wicked or immoral behavior [syn: misbehavior,
         misbehaviour, misdeed]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

MISBEHAVIOUR. Improper or unlawful conduct. See 2 Mart. N. S. 683.
     2. A party guilty of misbehaviour; as, for example, to threaten to do
injury to another, may be bound to his good behaviour and thus restrained.
See Good Behaviour.
     3. Verdicts are not unfrequently set aside on the ground of
misbehaviour of jurors; as, when the jury take out with them papers which
were not given in evidence, to the prejudice of one of the parties. Ld.
Raym. 148. When they separate before they have agreed upon their verdict. 3
Day, 237, 310., When they cast lots for a verdict; 2 Lev. 205; or, give
their verdict because they have agreed to give it for the amount ascertained
by each juror putting down a sum, adding the whole together, and then
dividing by twelve the number of jurors, and giving their verdict for the
quotient. 15 John. 87. See Bac. Ab. Verdict, H.
     4. A verdict will be set aside if the successful party has been guilty
of any misbehaviour towards the jury; as, if he say to a juror, "I hope you
will find a verdict for me;" or "the matter is clearly of my side." 1 Vent.
125; 2 Roll. Ab. 716, pl. 17. See Code, 166, 401; Bac. Ab. Verdict, I.