Vicissitude noun vi·cis·si·tude \və-ˈsi-sə-ˌtüd, vī-, -ˌtyüd\ Definition of VICISSITUDE 1 a :  the quality or state of being changeable :  mutability b :  natural change or mutation visible in nature or in human affairs 2 a :  a favorable or unfavorable event or situation that occurs by chance :  a fluctuation of state or condition <the vicissitudes of daily life> b :  a difficulty or hardship attendant on a way of life, a career, or a course of action and usually beyond one’s control c :  alternating change :  succession