Source : Webster's Revised Unabridged Dictionary (1913)

Annoyance \An*noy"ance\, n. [OF. anoiance, anuiance.]
   1. The act of annoying, or the state of being annoyed;
      molestation; vexation; annoy.

            A deep clay, giving much annoyance to passengers.
                                                  --Fuller.

            For the further annoyance and terror of any besieged
            place, they would throw into it dead bodies.
                                                  --Wilkins.

   2. That which annoys.

            A grain, a dust, a gnat, a wandering hair, Any
            annoyance in that precious sense.     --Shak.

Source : WordNet®

annoyance
     n 1: the psychological state of being irritated or annoyed [syn:
          {irritation}, {vexation}, {botheration}]
     2: anger produced by some annoying irritation [syn: {chafe}, {vexation}]
     3: an unpleasant person who is annoying or exasperating [syn: {aggravator}]
     4: something or someone that causes trouble; a source of
        unhappiness; "washing dishes was a nuisance before we got
        a dish washer"; "a bit of a bother"; "he's not a friend,
        he's an infliction" [syn: {bother}, {botheration}, {pain},
         {infliction}, {pain in the neck}, {pain in the ass}]
     5: the act of troubling or annoying someone [syn: {annoying}, {irritation},
         {vexation}]