fickleness (part of speech: noun)
irregularity (part of speech: noun)
- By and by she had a lover, but no sooner did he show tokens of inconstancy, than the mother came up from the sea and put him to death, when the daughter pined away and died. - "Sintram and His Companions", Friedrich de la Motte Fouque Commentator: Charlotte M. Yonge.
- But, have I not reason to complain of this inconstancy, on your part? - "The Water-Witch or, The Skimmer of the Seas", James Fenimore Cooper.
- For them his vices, his treachery, his heartlessness, have nothing repellent; nor does his inconstancy rob him of feminine sympathy. - "The Land of The Blessed Virgin; Sketches and Impressions in Andalusia", William Somerset Maugham.