The quality of being unreliable, unpredictable, or prone to changing one's mind, loyalty, or affections without good reason.
From 'fickle' (Old English 'ficol,' meaning deceitful) plus the abstract noun suffix '-ness,' creating a noun for the trait of being changeable.
Medieval writers blamed fickleness on the moon and planets, thinking the stars made people emotionally unstable—they didn't realize they were describing human nature!
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