accidentally

adjective

1. happening by chance or accident; not planned; unexpected: an accidental meeting.
2. nonessential; incidental; subsidiary: accidental benefits.
3. Music. relating to or indicating sharps, flats, or naturals.

noun

4. a nonessential or subsidiary circumstance, characteristic, or feature.
5. Music. a sign placed before a note indicating a chromatic alteration of its pitch.

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

noun

5. an incidental, nonessential, or supplementary circumstance, factor, or attribute
6. music a symbol denoting a sharp, flat, or natural that is not a part of the key signature

adv.

late 14c., “non-essentially,” also “unnaturally,” from accidental + -ly (2). Meaning “unintentionally” is recorded from 1580s; phrase accidentally on purpose is recorded from 1862.

adj.

late 14c., “non-essential,” from Old French accidentel or directly from Medieval Latin accidentalis, from Latin accidentem (see accident). Meaning “outside the normal course of nature” is from early 15c.; that of “coming by chance” is from 1570s.

n.

late 14c., “non-essential quality,” from accidental (adj.). The musical sense is from 1868.