Vicissitude

Part of speech: noun (n.)

1. Regular change or succession from one thing to another; alternation; mutual succession; interchange. God made two great lights . . . To illuminate the earth and rule the day In their vicissitude, and rule the night. Milton.

2. Irregular change; revolution; mutation. This man had, after many vicissitudes of fortune, sunk at last into abject and hopeless poverty. Macaulay.