The Collaborative International Dictionary of English v.0.48:

External \Ex*ter"nal\, n.
   Something external or without; outward part; that which makes
   a show, rather than that which is intrinsic; visible form; --
   usually in the plural.
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         Adam was then no less glorious in his externals
                                                  --South.
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         God in externals could not place content. --Pope.
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The Collaborative International Dictionary of English v.0.48:

External \Ex*ter"nal\, a. [L. externus, fr. exter, exterus, on
   the outside, outward. See Exterior.]
   1. Outward; exterior; relating to the outside, as of a body;
      being without; acting from without; -- opposed to
      internal; as, the external form or surface of a body.
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            Of all external things, . . .
            She [Fancy] forms imaginations, aery shapes.
                                                  --Milton.
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   2. Outside of or separate from ourselves; (Metaph.) separate
      from the perceiving mind.
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   3. Outwardly perceptible; visible; physical or corporeal, as
      distinguished from mental or moral.
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            Her virtues graced with external gifts. --Shak.
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   4. Not intrinsic nor essential; accidental; accompanying;
      superficial.
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            The external circumstances are greatly different.
                                                  --Trench.
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   5. Foreign; relating to or connected with foreign nations;
      as, external trade or commerce; the external relations of
      a state or kingdom.
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   6. (Anat.) Away from the mesial plane of the body; lateral.
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   External angles. (Geom.) See under Angle.
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WordNet (r) 3.0 (2006):

external
    adj 1: happening or arising or located outside or beyond some
           limits or especially surface; "the external auditory
           canal"; "external pressures" [ant: internal]
    2: coming from the outside; "extraneous light in the camera
       spoiled the photograph"; "relying upon an extraneous income";
       "disdaining outside pressure groups" [syn: external,
       extraneous, outside]
    3: from or between other countries; "external commerce";
       "international trade"; "developing nations need outside help"
       [syn: external, international, outside(a)]
    4: purely outward or superficial; "external composure"; "an
       external concern for reputation"- A.R.Gurney,Jr.
    n 1: outward features; "he enjoyed the solemn externals of
         religion"

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "external":
   alien, apparent, border, circumference, cortex, cortical, covering,
   crust, envelope, epidermic, epidermis, exomorphic, exotic,
   exterior, extraneous, extraorganismal, extrinsic, facade, face,
   facet, foreign, fringe, front, impersonal, integument, lineaments,
   nonsubjective, objective, open, out, outer, outer face,
   outer layer, outer side, outer skin, outermost, outline, outlying,
   outmost, outside, outstanding, outward, outward-facing, over,
   perceptible, peripheral, periphery, public, rind, roundabout,
   seeming, shell, skin, superficial, superficies, superstratum,
   surface, top, visible