Dictionary.com
Thesaurus.com
Synonyms

accidental

American  
[ak-si-den-tl] / ˌæk sɪˈdɛn tl /

adjective

  1. happening by chance or accident; not planned; unexpected.

    an accidental meeting.

    Synonyms:
    unintentional
    Antonyms:
    contrived, planned
  2. nonessential; incidental; subsidiary.

    accidental benefits.

  3. Music. relating to or indicating sharps, flats, or naturals.


noun

  1. a nonessential or subsidiary circumstance, characteristic, or feature.

  2. Music. a sign placed before a note indicating a chromatic alteration of its pitch.

accidental British  
/ ˌæksɪˈdɛntəl /

adjective

  1. occurring by chance, unexpectedly, or unintentionally

  2. nonessential; incidental

  3. music denoting sharps, flats, or naturals that are not in the key signature of a piece

  4. logic (of a property) not essential; contingent

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

noun

  1. an incidental, nonessential, or supplementary circumstance, factor, or attribute

  2. music a symbol denoting a sharp, flat, or natural that is not a part of the key signature

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Usage

What does accidental mean? Accidental describes something that happens by chance or without planning, as in The hero has an accidental meeting with the villain early in the movie that sets the hero on his course. Accidental can also sometimes refer to something that comes about by chance. Example: We had to sign a contract saying we are aware of the possibility of accidental injury.

Related Words

Accidental, casual, fortuitous all describe something outside the usual course of events. Accidental implies occurring unexpectedly or by chance: an accidental blow. Casual describes a passing event of slight importance: a casual reference. Fortuitous is applied to events occurring without known cause, often of a fortunate or favorable nature: a fortuitous shower of meteors. It often also implies good luck or good fortune: a fortuitous choice leading to rapid advancement.

Other Word Forms

  • accidentality noun
  • accidentally adverb
  • accidentalness noun
  • accidently adverb
  • nonaccidental adjective
  • nonaccidentalness noun
  • preaccidental adjective
  • pseudoaccidental adjective
  • quasi-accidental adjective
  • unaccidental adjective

Etymology

Origin of accidental

First recorded in 1350–1400; Middle English word from Medieval Latin word accidentālis. See accident, -al 1

Explanation

Anything accidental happens by chance or unintentionally. People don't mean to do accidental things. An accident is something unforeseen that no one wanted to happen, like a car accident or getting hit by lightning. You can describe anything like that as accidental. Bumping into a stranger could be accidental. Forgetting to pay a bill is accidental. This word covers all the things that no one really meant or planned to happen. There are a lot of accidental events in the world, which is one reason insurance exists.

Keep Reading on Vocabulary.com

Vocabulary lists containing accidental

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

O’Mahony considers the installation Coachella’s accidental town hall.

From Los Angeles Times • Apr. 10, 2026

Many U.S. innovations, including medical devices and household items, originated from accidental discoveries or mistakes.

From The Wall Street Journal • Apr. 4, 2026

"When I saw the footage, it was immediately clear that this was not accidental," Auersperg says.

From Science Daily • Mar. 26, 2026

Indian singer-composer Zubeen Garg's drowning last year in Singapore was accidental and there is no evidence of foul play, a coroner's inquiry has found.

From BBC • Mar. 25, 2026

As it happens, Feldmans accidental study provides a window onto a form of cheating that has long stymied academics: white- collar crime.

From "Freakonomics: A Rogue Economist Explores the Hidden Side of Everything" by Steven D. Levitt