A quirk of fate is an unexpected and often unpredictable event that can have a major impact on someone's life. It is often seen as a coincidence or a twist of fate. The term 'quirk of fate' can be used to describe a situation in which something happens that was not planned or expected. The crossword solution for the term 'quirk of fate' is 'FLUKE, ' which is defined as an unexpected, usually fortunate occurrence.