accidental accidental /ˌæksɪˈdɛntl/

adjective

1. Not of prime or central importance  ( accidental , incidental , nonessential )
   not of prime or central importance
    Nonessential to the integral meanings of poetry
   nonessential to the integral meanings of poetry
    The character's motives remain accidental to the plot
   the character's motives remain accidental to the plot
   
2. Happening by chance, unexpectedly or unintentionally  ( accidental , inadvertent )
   happening by chance, unexpectedly or unintentionally
    With an inadvertent gesture she swept the vase off the table
   with an inadvertent gesture she swept the vase off the table
    Accidental poisoning
   accidental poisoning
    An accidental shooting
   an accidental shooting
   

noun

1. A musical notation that makes a note sharp, flat or natural although that is not part of the key signature  ( accidental )
   a musical notation that makes a note sharp, flat or natural although that is not part of the key signature