As an adjective:
* The accidental discovery of penicillin revolutionized medicine.
* She made an accidental purchase while browsing online.
* The accidental fire caused significant damage to the building.
As an adverb:
* He accidentally spilled coffee on his new shirt.
* The car accidentally veered off the road.
* I accidentally deleted the important file.
In a phrase:
* It was just an accident; there was no malice involved.
* The accident happened at a busy intersection.
* The accident was caused by a mechanical failure.
In a different context:
* The musician used an accidental to add a surprising twist to the melody. (Here, "accidental" refers to a musical term).
* The witness's testimony was accidental to the investigation. (Here, "accidental" means unintentional or unplanned).
You can choose the best way to use "accidental" based on the specific meaning and context you want to convey.