The Collaborative International Dictionary of English v.0.48:

Deflection \De*flec"tion\, n. [L. deflexio, fr. deflectere: cf.
   F. d['e]flexion.]
   1. The act of turning aside, or state of being turned aside;
      a turning from a right line or proper course; a bending,
      esp. downward; deviation.
      [1913 Webster]

            The other leads to the same point, through certain
            deflections.                          --Lowth.
      [1913 Webster]

   2. (Gunnery) The deviation of a shot or ball from its true
      course.
      [1913 Webster]

   3. (Opt.) A deviation of the rays of light toward the surface
      of an opaque body; inflection; diffraction.
      [1913 Webster]

   4. (Engin.) The bending which a beam or girder undergoes from
      its own weight or by reason of a load.
      [1913 Webster]

WordNet (r) 3.0 (2006):

deflection
    n 1: a twist or aberration; especially a perverse or abnormal
         way of judging or acting [syn: deflection, warp]
    2: the amount by which a propagating wave is bent [syn:
       deflection, deflexion, refraction]
    3: the movement of the pointer or pen of a measuring instrument
       from its zero position [syn: deflection, deflexion]
    4: the property of being bent or deflected [syn: deflection,
       deflexion, bending]
    5: a turning aside (of your course or attention or concern); "a
       diversion from the main highway"; "a digression into
       irrelevant details"; "a deflection from his goal" [syn:
       diversion, deviation, digression, deflection,
       deflexion, divagation]

Moby Thesaurus II by Grady Ward, 1.0:

96 Moby Thesaurus words for "deflection":
   L, S-curve, aberration, angle, apex, atmospheric attenuation, bend,
   bending, bifurcation, bight, blind spots, bow, bowing, cant,
   chevron, circuitousness, clutter, coin, conflexure, corner, crank,
   crook, crosswiseness, crotchet, declination, defile, deflexure,
   deflower, departing, departure, deviance, deviation, deviousness,
   diagonality, diffraction, diffusion, digression, dispersion,
   distortion, divagation, divergence, diversion, dogleg, elbow, ell,
   excursion, false echoes, flection, flex, flexure, force, fork,
   furcation, geanticline, geosyncline, ground clutter, hairpin turn,
   hook, indirection, indirectness, inflection, knee, meander,
   nonconformity, nook, obliqueness, obliquity, outrage, oxbow, point,
   quoin, ravish, reflection, refraction, scatter, sea clutter,
   skewness, spoil, squint, superrefraction, sweep, swerve, swerving,
   torsion, transverseness, turn, turning, twisting, vagary, veer,
   veering, vertex, violate, zag, zig, zigzag