The Collaborative International Dictionary of English v.0.48:

Meerkat \Meer"kat\ (m[=e]r"k[a^]t), n. [D.] (Zool.)
   A South African carnivore (Suricata suricata, formerly
   Cynictis penicillata), allied to the ichneumons, having a
   lemurlike face and only four toes; called also yellow
   mongoose and suricate. [Also spelled mierkat.]
   [1913 Webster]

         While his compatrioits scuffle about in the sand for
         delicious scorpions or fat, tasty mice, one meerkat
         stands alone, bolt upright on an exposed perch,
         scanning for hawks with dark eyes wide, ready to call
         out at the first sign of danger. Like other such guards
         in the animal kingdom, these endearingly vulnerable
         meerkat sentinels have long impressed biologists as
         true altruists -- creatures willing to forgo food and
         brave danger to protect others.
         Now a study in the current Science suggests that these
         beasts may not be such adorable heroes after all.
         Researchers have discovered that meerkats abandon their
         hunting to act as guards only when their bellies are
         good and full. And they appear to do so, not as an act
         of noble daring, but because by being the first to see
         a predator, they can be sure of being the first down a
         hole and out of harm's way. Standing guard, researchers
         concluded, may be the safest thing to do once a meerkat
         has had enough to eat.
         . . .
         Even the adorable meerkat may yet redeem itself as a
         bit of an altruist. Although being a sentinel may
         itself not entail great risk, it is hard to imagine a
         selfish reason for their giving a shout of warning
         before dashing for cover. . . .          --Carol Kaesuk
                                                  Yoon (N. Y.
                                                  Times, June 8,
                                                  1999 p. F3)
   [PJC]

The Collaborative International Dictionary of English v.0.48:

mierkat \mierkat\ n. (Zool.)
   A South African mongooselike viverrine (Suricata suricata)
   having a lemurlike face and only four toes; called also
   suricate. [Also spelled meerkat.]

   Syn: meerkat.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

meerkat
    n 1: a mongoose-like viverrine of South Africa having a face
         like a lemur and only four toes [syn: meerkat, mierkat]