What is the meaning of the word "vicissitude"?

Definitions:

  1. a variation in circumstances or fortune at different times in your life or in the development of something copy to clipboard noun
    • The project was subject to the usual vicissitudes of exploratory research. copy to clipboard
  2. mutability in life or nature, especially successive alternation from one condition to another copy to clipboard noun
    • The lifecycle of a butterfly shows the vicissitudes of animal life. copy to clipboard