ADJECTIVE (3)

1. tending to intrude (especially upon privacy);
- Example: "she felt her presence there was intrusive"

2. of rock material; forced while molten into cracks between layers of other rock;

3. thrusting inward;
- Example: "an intrusive arm of the sea"

The Collaborative International Dictionary of English v.0.48:

Intrusive \In*tru"sive\, a.
   Apt to intrude; characterized by intrusion; entering without
   right or welcome.
   [1913 Webster]

   Intrusive rocks (Geol.), rocks which have been forced,
      while in a plastic or melted state, into the cavities or
      between the cracks or layers of other rocks. The term is
      sometimes used as equivalent to plutonic rocks. It is
      then contrasted with effusive or volcanic rocks. --
      In*tru"sive*ly, adv. -- In*tru"sive*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

intrusive
    adj 1: tending to intrude (especially upon privacy); "she felt
           her presence there was intrusive" [ant: not intrusive,
           unintrusive]
    2: of rock material; forced while molten into cracks between
       layers of other rock [ant: extrusive]
    3: thrusting inward; "an intrusive arm of the sea" [ant:
       protrusive]

Moby Thesaurus II by Grady Ward, 1.0:

97 Moby Thesaurus words for "intrusive":
   alien, barbarian, barbaric, barbarous, busy, entering, exotic,
   exterior, external, extraneous, extraterrestrial, extrinsic,
   foreign, foreign-born, forward, frantic, frenetic, frenzied,
   hectic, hyperactive, hyperkinetic, ill-considered, ill-seasoned,
   ill-timed, importunate, improper, in, inappropriate, inauspicious,
   inbound, incoming, inconvenient, inexpedient, infelicitous,
   inflooding, inflowing, ingoing, ingressive, inopportune, inpouring,
   inquisitive, intempestive, interfering, interruptive, intervenient,
   intruding, invasive, inward, inward-bound, irrelevant, irruptive,
   late, mal a propos, malapropos, meddlesome, meddling, mistimed,
   nosy, obtrusive, off base, officious, out of line, out of phase,
   out of time, outland, outlandish, outside, premature, presumptuous,
   prying, pushy, snoopy, strange, too late, too soon, ulterior,
   unbefitting, uncalled-for, unearthly, unfavorable, unfit,
   unfitting, unfortunate, unhandy, unhappy, unlucky, unpropitious,
   unready, unripe, unseasonable, unsought, unsuitable, untimely,
   untoward, unwanted, unwelcome, wrong