The Collaborative International Dictionary of English v.0.48:

Terrestrial \Ter*res"tri*al\, a. [L. terrestris, from terra the
   earth. See Terrace.]
   1. Of or pertaining to the earth; existing on the earth;
      earthly; as, terrestrial animals. "Bodies terrestrial."
      --1 Cor. xv. 40.
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   2. Representing, or consisting of, the earth; as, a
      terrestrial globe. "The dark terrestrial ball." --Addison.
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   3. Of or pertaining to the world, or to the present state;
      sublunary; mundane.
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            Vain labors of terrestrial wit.       --Spenser.
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            A genius bright and base,
            Of towering talents, and terrestrial aims. --Young.
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   4. Consisting of land, in distinction from water; belonging
      to, or inhabiting, the land or ground, in distinction from
      trees, water, or the like; as, terrestrial serpents.
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            The terrestrial parts of the globe.   --Woodward.
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   5. Adapted for the observation of objects on land and on the
      earth; as, a terrestrial telescope, in distinction from an
      astronomical telescope.
      [1913 Webster] -- Ter*res"tri*al*ly, adv. --
      Ter*res"tri*al*ness, n.
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The Collaborative International Dictionary of English v.0.48:

Terrestrial \Ter*res"tri*al\, n.
   An inhabitant of the earth.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

eyepiece \eye"piece`\ eye-piece \eye"-piece`\, n. (Opt.)
   The lens, or combination of lenses, at the eye end of a
   microscope, telescope or other optical instrument, through
   which the image formed by the mirror or object glass is
   viewed.

   Syn: ocular.
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   Collimating eyepiece. See under Collimate.

   Negative, or Huyghenian, eyepiece, an eyepiece
      consisting of two plano-convex lenses with their curved
      surfaces turned toward the object glass, and separated
      from each other by about half the sum of their focal
      distances, the image viewed by the eye being formed
      between the two lenses. it was devised by Huyghens, who
      applied it to the telescope. Campani applied it to the
      microscope, whence it is sometimes called Campani's
      eyepiece.

   Positive eyepiece, an eyepiece consisting of two
      plano-convex lenses placed with their curved surfaces
      toward each other, and separated by a distance somewhat
      less than the focal distance of the one nearest eye, the
      image of the object viewed being beyond both lenses; --
      called also, from the name of the inventor, Ramsden's
      eyepiece.

   terrestrial, or Erecting eyepiece, an eyepiece used in
      telescopes for viewing terrestrial objects, consisting of
      three, or usually four, lenses, so arranged as to present
      the image of the object viewed in an erect position.
      [1913 Webster]

WordNet (r) 3.0 (2006):

terrestrial
    adj 1: of or relating to or inhabiting the land as opposed to
           the sea or air [syn: tellurian, telluric,
           terrestrial, terrene]
    2: of or relating to or characteristic of the planet Earth or
       its inhabitants; "planetary rumblings and eructations"-
       L.C.Eiseley ; "the planetary tilt"; "this terrestrial ball"
       [syn: planetary, terrestrial]
    3: operating or living or growing on land [ant: amphibious,
       aquatic]
    4: concerned with the world or worldly matters; "mundane
       affairs"; "he developed an immense terrestrial practicality"
       [syn: mundane, terrestrial]
    5: of this earth; "transcendental motives for sublunary
       actions"; "fleeting sublunary pleasures"; "the nearest to an
       angelic being that treads this terrestrial ball" [syn:
       sublunar, sublunary, terrestrial]

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "terrestrial":
   Cynthian, Philistine, anagalactic, asteroidal, astral, astrologic,
   astrologistic, astrologous, astronomic, astrophysical, carnal,
   carnal-minded, celestial, circumplanetary, cislunar, earth,
   earthbound, earthling, earthly, earthy, empyreal, empyrean,
   equinoctial, extragalactic, fluvioterrestrial, galactic,
   geophilous, global, heavenly, heliacal, human, intercosmic,
   interplanetary, intersidereal, interstellar, lunar, lunary, lunate,
   lunular, lunulate, material, materialistic, meteoric, meteoritic,
   mortal, mundane, nebular, nebulose, nebulous, planetal,
   planetarian, planetary, planetesimal, profane, prosaic, secular,
   semilunar, sidereal, solar, sphery, star-spangled, star-studded,
   starry, stellar, stellary, subastral, sublunar, tellurian,
   telluric, temporal, terraqueous, terrene, unspiritual, uranic,
   worldly, zodiacal