Not part of the real or essential nature of a thing
He also wrote incidental music to Hamlet, a symphony, and other works.
Grasserie is another form of disease incidental to the silkworm.
The incidental historical notices, which are often of great value and interest, are all his own.
But all pain and sorrow are incidental to the human being in his individual capacity.
The figure ten may be taken from the commandments, 2 as in Gregory Nazianzen's later, and more incidental, decalogue of belief.