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.
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   2. (Gunnery) The deviation of a shot or ball from its true
      course.
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   3. (Opt.) A deviation of the rays of light toward the surface
      of an opaque body; inflection; diffraction.
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   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]