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.

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noun

accidentals plural

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

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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

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.

Synonym Usage

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

Derived Forms

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

Inflected Forms

Nouns

• accidentals
  plural

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.

Example Sentences

There’s a great accidental gag in a cut bit from the original MTV pilot when a deputy pulls up to arrest Knoxville and forgets to put her car in park.

From Los Angeles Times • Jun. 26, 2026

There is nothing accidental about the dollar’s place in the world, and our leadership role comes with enormous advantages.

From The Wall Street Journal • Jun. 23, 2026

The population collapse has been caused primarily by accidental entanglement in gillnets, especially those used to illegally catch totoaba.

From Science Daily • Jun. 17, 2026

These are no ordinary switches: they are physically latched, protected by locking mechanisms and designed to require deliberate action, precisely to prevent accidental engine shutdown.

From BBC • Jun. 15, 2026

Just as Olmsted sought to conjure an aura of mystery in his landscape, so here he urged the engineering of seemingly accidental moments of charm.

From "The Devil in the White City" by Erik Larson

Related Words

• coincidental
• inadvertent
• incidental
• random
• unexpected
• unforeseen
• unintended
• unintentional
• unplanned