The Collaborative International Dictionary of English v.0.48:

Reflection \Re*flec"tion\ (r?*fl?k"sh?n), n. [L. reflexio: cf.
   F. r['e]flexion. See Riflect.] [Written also reflexion.]
   1. The act of reflecting, or turning or sending back, or the
      state of being reflected. Specifically:
      (a) The return of rays, beams, sound, or the like, from a
          surface. See Angle of reflection, below.
          [1913 Webster]

                The eye sees not itself,
                But by reflection, by some other things. --Shak.
          [1913 Webster]
      (b) The reverting of the mind to that which has already
          occupied it; continued consideration; meditation;
          contemplation; hence, also, that operation or power of
          the mind by which it is conscious of its own acts or
          states; the capacity for judging rationally,
          especially in view of a moral rule or standard.
          [1913 Webster]

                By reflection, . . . I would be understood to
                mean, that notice which the mind takes of its
                own operations, and the manner of them, by
                reason whereof there come to be ideas of these
                operations in the understanding.  --Locke.
          [1913 Webster]

                This delight grows and improves under thought
                and reflection.                   --South.
          [1913 Webster]

   2. Shining; brightness, as of the sun. [Obs.] --Shak.
      [1913 Webster]

   3. That which is produced by reflection. Specifically:
      (a) An image given back from a reflecting surface; a
          reflected counterpart.
          [1913 Webster]

                As the sun water we can bear,
                Yet not the sun, but his reflection, there.
                                                  --Dryden.
          [1913 Webster]
      (b) A part reflected, or turned back, at an angle; as, the
          reflection of a membrane.
      (c) Result of meditation; thought or opinion after
          attentive consideration or contemplation; especially,
          thoughts suggested by truth.
          [1913 Webster]

                Job's reflections on his once flourishing estate
                did at the same time afflict and encourage him.
                                                  --Atterbury.
          [1913 Webster]

   4. Censure; reproach cast.
      [1913 Webster]

            He died; and oh! may no reflection shed
            Its poisonous venom on the royal dead. --Prior.
      [1913 Webster]

   5. (Physiol.) The transference of an excitement from one
      nerve fiber to another by means of the nerve cells, as in
      reflex action. See Reflex action, under Reflex.
      [1913 Webster]

   Angle of reflection, the angle which anything, as a ray of
      light, on leaving a reflecting surface, makes with the
      perpendicular to the surface.

   Angle of total reflection. (Opt.) Same as Critical angle,
      under Critical.
      [1913 Webster]

   Syn: Meditation; contemplation; rumination; cogitation;
        consideration; musing; thinking.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Angle \An"gle\ ([a^][ng]"g'l), n. [F. angle, L. angulus angle,
   corner; akin to uncus hook, Gr. 'agky`los bent, crooked,
   angular, 'a`gkos a bend or hollow, AS. angel hook, fish-hook,
   G. angel, and F. anchor.]
   1. The inclosed space near the point where two lines meet; a
      corner; a nook.
      [1913 Webster]

            Into the utmost angle of the world.   --Spenser.
      [1913 Webster]

            To search the tenderest angles of the heart.
                                                  --Milton.
      [1913 Webster]

   2. (Geom.)
      (a) The figure made by. two lines which meet.
      (b) The difference of direction of two lines. In the lines
          meet, the point of meeting is the vertex of the angle.
          [1913 Webster]

   3. A projecting or sharp corner; an angular fragment.
      [1913 Webster]

            Though but an angle reached him of the stone.
                                                  --Dryden.
      [1913 Webster]

   4. (Astrol.) A name given to four of the twelve astrological
      "houses." [Obs.] --Chaucer.
      [1913 Webster]

   5. [AS. angel.] A fishhook; tackle for catching fish,
      consisting of a line, hook, and bait, with or without a
      rod.
      [1913 Webster]

            Give me mine angle: we 'll to the river there.
                                                  --Shak.
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            A fisher next his trembling angle bears. --Pope.
      [1913 Webster]

   Acute angle, one less than a right angle, or less than
      90[deg].

   Adjacent or Contiguous angles, such as have one leg
      common to both angles.

   Alternate angles. See Alternate.

   Angle bar.
      (a) (Carp.) An upright bar at the angle where two faces of
          a polygonal or bay window meet. --Knight.
      (b) (Mach.) Same as Angle iron.

   Angle bead (Arch.), a bead worked on or fixed to the angle
      of any architectural work, esp. for protecting an angle of
      a wall.

   Angle brace, Angle tie (Carp.), a brace across an
      interior angle of a wooden frame, forming the hypothenuse
      and securing the two side pieces together. --Knight.

   Angle iron (Mach.), a rolled bar or plate of iron having
      one or more angles, used for forming the corners, or
      connecting or sustaining the sides of an iron structure to
      which it is riveted.

   Angle leaf (Arch.), a detail in the form of a leaf, more or
      less conventionalized, used to decorate and sometimes to
      strengthen an angle.

   Angle meter, an instrument for measuring angles, esp. for
      ascertaining the dip of strata.

   Angle shaft (Arch.), an enriched angle bead, often having a
      capital or base, or both.

   Curvilineal angle, one formed by two curved lines.

   External angles, angles formed by the sides of any
      right-lined figure, when the sides are produced or
      lengthened.

   Facial angle. See under Facial.

   Internal angles, those which are within any right-lined
      figure.

   Mixtilineal angle, one formed by a right line with a curved
      line.

   Oblique angle, one acute or obtuse, in opposition to a
      right angle.

   Obtuse angle, one greater than a right angle, or more than
      90[deg].

   Optic angle. See under Optic.

   Rectilineal or Right-lined angle, one formed by two right
      lines.

   Right angle, one formed by a right line falling on another
      perpendicularly, or an angle of 90[deg] (measured by a
      quarter circle).

   Solid angle, the figure formed by the meeting of three or
      more plane angles at one point.

   Spherical angle, one made by the meeting of two arcs of
      great circles, which mutually cut one another on the
      surface of a globe or sphere.

   Visual angle, the angle formed by two rays of light, or two
      straight lines drawn from the extreme points of an object
      to the center of the eye.

   For Angles of commutation, draught, incidence,
   reflection, refraction, position, repose, fraction,
      see Commutation, Draught, Incidence, Reflection,
      Refraction, etc.
      [1913 Webster]

WordNet (r) 3.0 (2006):

reflection
    n 1: a calm, lengthy, intent consideration [syn:
         contemplation, reflection, reflexion, rumination,
         musing, thoughtfulness]
    2: the phenomenon of a propagating wave (light or sound) being
       thrown back from a surface [syn: reflection, reflexion]
    3: expression without words; "tears are an expression of grief";
       "the pulse is a reflection of the heart's condition" [syn:
       expression, manifestation, reflection, reflexion]
    4: a likeness in which left and right are reversed [syn: mirror
       image, reflection, reflexion]
    5: the image of something as reflected by a mirror (or other
       reflective material); "he studied his reflection in the
       mirror" [syn: reflection, reflexion]
    6: (mathematics) a transformation in which the direction of one
       axis is reversed
    7: a remark expressing careful consideration [syn:
       observation, reflection, reflexion]
    8: the ability to reflect beams or rays [syn: reflection,
       reflexion, reflectivity]

Moby Thesaurus II by Grady Ward, 1.0:

322 Moby Thesaurus words for "reflection":
   CRT spot, DM display, Doppler signal, IF signal, IM display,
   Parthian shot, RF echoes, S-curve, action and reaction, address,
   adumbration, adverse criticism, advisement, affirmation, albedo,
   allegation, animadversion, answer, apostrophe, apprehension,
   aspersion, assault, assertion, attack, attaint, automatic reaction,
   autonomic reaction, averment, bad notices, bad press,
   badge of infamy, bar sinister, baton, beam, beat signal, bend,
   bend sinister, bending, black eye, black mark, blink, blips, blot,
   blur, bounceback, bounces, bow, bowing, brainwork, brand,
   broad arrow, brooding, captiousness, carping, cavil, caviling,
   censoriousness, censure, cerebration, champain, circumspection,
   circumspectness, cogitation, comment, commitment to memory,
   companion, conceit, concept, conception, conflexure, consideration,
   contemplation, cool judgment, copy, corroboration, counsel, crack,
   criticism, dead ringer, declaration, deflection, deliberating,
   deliberation, depreciation, derogation, dictum, discreetness,
   discretion, discrimination, disparagement, display, double,
   double-dot display, duplicate, echo, echo signal, effect, effigy,
   evidence, exact likeness, exception, exclamation,
   exercise of memory, expression, fancy, faultfinding, fellow, flak,
   flashback, flection, flex, flexure, geanticline, geosyncline,
   good judgment, greeting, hairpin turn, hairsplitting, hindsight,
   hit, home thrust, hostile criticism, hypercriticalness,
   hypercriticism, ice sky, iceblink, icon, idea, idol, image, imago,
   impression, imputation, incident light, inflection, innuendo,
   insinuation, intellectual object, interjection, judgment,
   judiciousness, knock, learning by heart, likeness, living image,
   living picture, local oscillator signal, looking back, lucubration,
   mark, mark of Cain, match, mate, meander, meditating, meditation,
   memoir, memorization, memorizing, memory-trace, mental image,
   mental impression, mention, miniature, mirroring, model, musing,
   nagging, niggle, niggling, nit, nit-picking, note, notion, obloquy,
   observation, onset, onslaught, onus, opinion, outline,
   output signal, overcriticalness, oxbow, perception,
   personal remark, personality, pestering, pettifogging, photograph,
   phrase, picture, pillorying, pips, point champain, policy, polity,
   pondering, portrait, position, predictable response, priggishness,
   pronouncement, proof, providence, prudence, prudentialism,
   question, quibble, quibbling, radar signal, rap, reaction, reading,
   recall, recalling, recept, recollecting, recollection,
   reconsideration, reflectance, reflectiveness, reflex,
   reflex action, refluence, reflux, remark, remembering, remembrance,
   reminiscence, reply, representation, reprimand, reproach,
   reproachfulness, resemblance, respondence, response, result,
   retroaction, retrospect, retrospection, return, return signal,
   reverberation, review, revolving, revulsion, rise, rote,
   rote memory, rubbing, rumination, say, saying, semblance, sentence,
   sentiment, shadow, sign, signal, signal display, silhouette,
   similitude, simulacrum, slam, slur, sly suggestion, smear, smirch,
   smudge, smutch, snowblink, sound judgment, soundness of judgment,
   speculation, spit and image, spitting image, spot, stain,
   statement, stigma, stigmatism, stigmatization, stricture, study,
   subjoinder, substantiation, suggestion, supposition, sweep, swipe,
   symbol, taint, taking exception, target image, tarnish, testament,
   testimony, theory, thinking, thought, thoughtfulness, token, trace,
   tracing, transmitter signal, trichoschistism, turn, turning, twin,
   uncomplimentary remark, unthinking response, utterance, very image,
   very picture, video signal, water sky, waterblink, weighing,
   whispering campaign, word



The Devil's Dictionary (1881-1906):

REFLECTION, n.  An action of the mind whereby we obtain a clearer view
of our relation to the things of yesterday and are able to avoid the
perils that we shall not again encounter.