The Collaborative International Dictionary of English v.0.48:

Encroach \En*croach"\, n.
   Encroachment. [Obs.] --South.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Encroach \En*croach"\, v. i. [imp. & p. p. Encroached; p. pr.
   & vb. n. Encroaching.] [OF. encrochier to perch, prop., to
   hook, fasten a hook (perh. confused with acrochier, F.
   accrocher, to hook, get hold of, E. accroach); pref. en- (L.
   in) + F. croc hook. See Crook, and cf. Accroach.]
   To enter by gradual steps or by stealth into the possessions
   or rights of another; to trespass; to intrude; to trench; --
   commonly with on or upon; as, to encroach on a neighbor; to
   encroach on the highway.
   [1913 Webster]

         No sense, faculty, or member must encroach upon or
         interfere with the duty and office of another. --South.
   [1913 Webster]

         Superstition, . . . a creeping and encroaching evil.
                                                  --Hooker.
   [1913 Webster]

         Exclude the encroaching cattle from thy ground.
                                                  --Dryden.

   Syn: To intrude; trench; infringe; invade; trespass.
        [1913 Webster]

WordNet (r) 3.0 (2006):

encroach
    v 1: advance beyond the usual limit [syn: encroach,
         infringe, impinge]
    2: impinge or infringe upon; "This impinges on my rights as an
       individual"; "This matter entrenches on other domains" [syn:
       impinge, encroach, entrench, trench]

Moby Thesaurus II by Grady Ward, 1.0:

81 Moby Thesaurus words for "encroach":
   abuse a privilege, adopt, advance upon, appropriate, arrogate,
   assume, barge in, bother, break bounds, break in, break in upon,
   burst in, bust in, butt in, charge in, come between, crash,
   crash in, crash the gates, creep in, crowd in, cut in, edge in,
   elbow in, encroach upon, entrench, foist in, go too far, horn,
   horn in, impinge, impose, impose on, impose upon, inconvenience,
   infiltrate, infringe, insinuate, interfere, interlope, interpose,
   intervene, intrude, invade, irrupt, know no bounds, make an inroad,
   make free with, obtrude, obtrude upon, overstep,
   overstep the bounds, play God, press in, presume on, presume upon,
   pretend to, push in, put on, put upon, rush in, seize, slink in,
   slip in, smash in, sneak in, squeeze in, steal in, storm in,
   take a liberty, take liberties, take over, throng in, thrust in,
   transgress, trench, trespass, trouble, usurp, work in, worm in