The phrase "act of spontaneous" is not correct in English; it should be "act of spontaneity." You can use it when referring to an action that is performed impulsively or without premeditation.
Example: "The act of spontaneity led them to take an unplanned road trip."
Alternatives: "impulsive action" or "spontaneous act."
He understands it looks bad, this stealing of their child, but it was an act of spontaneous desperation.
Her prayer for help is answered in the most spectacular way — via an act of spontaneous arboreal combustion.
Finally, a chance to turn the page on contemptible name-calling, to celebrate the act of spontaneous play-calling.
Few movies exist independently and freely, moment to moment, emblazoned with the act of spontaneous creation, as does "The Arbalest".
In "an act of spontaneous grace," Geiger thrashes the duplicitous client and takes Ezra Matheson (and the violin case he's clutching) to the austere home he shares with a one-eyed cat.
The beautiful ride leaves you happy you didn't fall into any sinkhole, happy the lion no one told you about was busy on a gazelle and you didn't get caught on the way back by a friendly act of spontaneous local taxation on the road back.
Hence acts of spontaneous generosity such as the £60,000 he donated to charity for a one-minute kiss with Kate Moss which he "gifted" to Jemima Khan to enjoy, though detractors saw it as evidence merely of his genius for self-promotion.
This is a loud city all right, but decibels have nothing to do with decency, or the lack of it, and in the 10 years I've been here, I've seen countless acts of spontaneous humanity that belie New York's reputation for callous narcissism.
However, the most consistent symptom of depressive affect among Indigenous men was the feeling of a weakened spirit, frequent and heavy use of alcohol, marijuana and other substances and the conduct of acts of spontaneous violence.
Impulsive aggression as opposed to premeditated aggression is believed to arise from an inability to fully regulate negative emotion and often leads to acts of spontaneous violence [Davidson et al., 2000; Siever, 2008].
It was an act of grace: spontaneous, uplifting and undeserved.
