However vague the citizens were as to the nature of his wickedness, once they lost faith in him they lost it completely and with joy, and they welcomed an apparently spontaneously generated rumor that he had betrayed his benefactor, their beloved Dr. Pickerbaugh, by seducing Orchid.
There are no more uses of "spontaneous" in the book.
Show samples from other sources
The group broke into spontaneous laughter.
He bubbled with enthusiasms, and his faintest smile or lightest laugh seemed spontaneous and genuine.