1. most likely to change frequently, especially as regards one’s loyalties or affections; most inconstant or unreliable
Usage: superlative form of fickle

Examples

• She was the ficklest friend I ever had, switching allegiances every week.
• The weather in spring is often the ficklest of all seasons.
• He proved to be the ficklest supporter, abandoning the team after one loss.
• Among all the voters, young adults are often considered the ficklest demographic.
• The ficklest customers are those who change brands based on minor price differences.
• Her ficklest moods always came when she was stressed about work.