spontaneous

/spɑnˈteɪniəs/
adjective
  1. Done or happening in a natural, unplanned way, without being forced or thought about beforehand.
    • They made a spontaneous decision to go to the beach after work.
    • Her spontaneous laugh was so genuine that everyone around her smiled.
    • The audience gave a spontaneous round of applause at the end of the speech.
  2. Happening as a result of natural processes, without outside cause or intervention.
    • The chemical reaction was spontaneous and released a lot of heat.
    • Some plants show spontaneous movement when touched.
    • Spontaneous generation was once believed to explain how maggots appeared on meat.
What does "spontaneous" mean? | whatsthatwordmean | whatsthatwordmean