1. [n]  a reflex response to sudden pain
2. [v]  draw back, as with fear or pain; "she flinched when they showed the slaughtering of the calf"

Flinch
Hack journalist Jimmy Gage is disgraced when a letter from a so-called serial killer called the Eggman is declared a hoax by the police. Jimmy is convinced that the letter is genuine and tries to assemble evidence on his own--evidence that begins to point to his own brother, wealthy surgeon Jonathan Gage. But is he just jealous that his ex-wife has recently married the successful Jonathan, or are his suspicions valid...?

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1. \Flinch\, v. i. [imp. & p. p. {Flinched}; p. pr. & vb. n.
   {Flinching}.] [Prob. fr. OE. flecchen to waver, give way, F.
   fl['e]chir, fr. L. flectere to bend; but prob. influenced by
   E. blench. Cf. {Flex}.]
   1. To withdraw from any suffering or undertaking, from pain
      or danger; to fail in doing or perserving; to show signs
      of yielding or of suffering; to shrink; to wince; as, one
      of the parties flinched from the combat.
            A child, by a constant course of kindness, may be
            accustomed to bear very rough usage without
            flinching or complaining.             --Locke.
   2. (Croquet) To let the foot slip from a ball, when
      attempting to give a tight croquet.
   

2. \Flinch\, n.
   The act of flinching.