The Collaborative International Dictionary of English v.0.48:

Deforcement \De*force"ment\, n. [OF.] (Law)
      (a) A keeping out by force or wrong; a wrongful
          withholding, as of lands or tenements, to which
          another has a right.
      (b) (Scots Law) Resistance to an officer in the execution
          of law. --Burrill.
          [1913 Webster]

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

DEFORCEMENT, tort. In its most extensive sense it signifies the holding of
any lands or tenements to which another person has a right; Co. Litt. 277;
so that this includes, as well, an abatement, an intrusion, a disseisin, or
a discontinuance, as any other species of wrong whatsoever, by which the
owner of the freehold is kept out of possession. But, as contradistinguished
from the former, it is only such a detainer, of the freehold, from him who
has the right of property, as falls within none of the injuries above
mentioned. 3 Bl. Com. 173; Archb. Civ. Pl. 13; Dane's Ab. Index, h.t.



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

DEFORCEMENT, Scotch law. The opposition given, or resistance made, to
messengers or other officers, while they are employed in executing the law.
     2. This crime is punished by confiscation of movables, the one half to
the king, and the other to the creditor at whose suit the diligence is used.
Ersk. Pr. L. Scot. 4,4,32.