"a passing from one state to another," whether regular or not, 1560s, from French vicissitude (14c.), from Latin vicissitudinem (nominative vicissitudo) "change, interchange, alternation," from vicissim (adv.) "changeably, on the other hand, by turns, in turn," from vicis "a turn, change" (from PIE root *weik- (2) "to bend, to wind"). Related: Vicissitudes.
also *weig-, Proto-Indo-European root meaning "to bend, to wind."
It forms all or part of: vetch; vicar; vicarious; vice- "deputy, assistant, substitute;" viceregent; vice versa; vicissitude; weak; weakfish; week; wicker; wicket; witch hazel; wych.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit visti "changing, changeable;" Old English wac "weak, pliant, soft," wician "to give way, yield," wice "wych elm," Old Norse vikja "to bend, turn," Swedish viker "willow twig, wand," German wechsel "change."
c. 1300, "chance, luck as a force in human affairs," from Old French fortune "lot, good fortune, misfortune" (12c.), from Latin fortuna "chance, fate, good luck," from fors (genitive fortis) "chance, luck," possibly ultimately from PIE root *bher- (1) "to carry," also "to bear children," which is supported by de Vaan even though "The semantic shift from 'load' or 'the carrying' to 'chance, luck' is not obvious ...." The sense might be "that which is brought."
Sense of "owned wealth" is first found in Spenser; probably it evolved from senses of "one's condition or standing in life," hence "position as determined by wealth," then "wealth, large estate" itself. Often personified as a goddess; her wheel betokens vicissitude. Soldier of fortune is attested by 1660s. Fortune 500 "most profitable American companies" is 1955, from the list published annually in "Fortune" magazine. Fortune-hunter "one who seeks to marry for wealth" is from 1680s.