ENGLISH
REFERENCE

accidental

adj. · n.
US //ˌæksəˈdɛnəɫ// UK //ˌæksɪdˈɛntəl// ac·ci·den·tal
  1. 1 happening by chance (adj.)
    B1 Intermediate

    happening by chance or by mistake, rather than being planned.

    occurring by chance, unexpectedly, or without deliberate intent.

    Example

    The police believe the fire was accidental and started in the kitchen.

    Example

    The discovery of the ancient coins was entirely accidental, occurring while the construction crew was digging a trench for new water pipes.
  2. 2 music symbol (n.)
    C1 Advanced Technical Music

    a symbol like a sharp or flat that changes a note for a short time.

    a sign placed before a note which alters its pitch by a semitone, independent of the key signature.

    Example

    The pianist missed the accidental in the third bar and played a wrong note.

    Example

    The composer used frequent accidentals to create a sense of tonal instability throughout the second movement.

    Usage

    The noun refers to the symbol itself (the sharp, flat, or natural sign).
Show 1 more senseShow fewer
  1. 3 non-essential property (n.)
    C2 Proficiency Academic Formal Philosophy

    a quality or feature of something that is not necessary for it to be what it is.

    a property or attribute that is not part of the essential nature of a thing.

    Example

    The color of the car is an accidental; it doesn't change the fact that it is a car.

    Example

    In Aristotelian logic, an accidental is a quality that can be changed without the subject losing its fundamental identity.
Origin

From Middle English accidental, from Anglo-Norman accidentel, Middle French accidentel, accidental, and their source, Late Latin accidēntālis; corresponding to accident + -al.

Word family

© 2026 English Reference