Source : Webster's Revised Unabridged Dictionary (1913)

Encroachment \En*croach"ment\, n.
   1. The act of entering gradually or silently upon the rights
      or possessions of another; unlawful intrusion.

            An unconstitutional encroachment of military power
            on the civil establishment.           --Bancroft.

   2. That which is taken by encroaching on another.

   3. (Law) An unlawful diminution of the possessions of
      another.

Source : WordNet®

encroachment
     n 1: any entry into an area not previously occupied; "an invasion
          of tourists"; "an invasion of locusts" [syn: {invasion},
           {intrusion}]
     2: entry to another's property without right or permission
        [syn: {trespass}, {violation}, {intrusion}, {usurpation}]
     3: influencing strongly; "they resented the impingement of
        American values on European culture" [syn: {impingement},
        {impact}]