1. Occurring unexpectedly, unintentionally, or by chance.
2. Music Of or relating to an accidental.
3. Being an animal, especially a bird, that has strayed beyond its normal range.
1. A property, factor, or attribute that is not essential.
a. Any of various signs that indicate the alteration of a note by one or two semitones or the cancellation of a previous sign.
b. A note that has been marked with such a sign.
3. An animal that has strayed beyond its normal range.
ac′ci·dental·ly, ac′ci·dently adv.
Synonyms: accidental, fortuitous, contingent, incidental
These adjectives apply to what happens unintentionally. Accidental primarily refers to what occurs by chance: an accidental meeting.
It can also mean subordinate or nonessential: "Poetry is something to which words are the accidental, not by any means the essential form" (Frederick W. Robertson).
Fortuitous stresses chance even more strongly: "the happy combination of fortuitous circumstances" (Sir Walter Scott).
Contingent describes what is possible but uncertain because of unforeseen or uncontrollable factors: "The results of confession were not contingent, they were certain" (George Eliot).
Incidental refers to a minor or unanticipated result or accompaniment: "There is scarcely any practice which is so corrupt as not to produce some incidental good" (Enoch Mellor).
(click for a larger image)accidental
left to right: G natural, G flat, G sharp
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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