The quality of of being unwonted or unusual; deviation from custom or habit. (noun)
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Use "unwontedness" in a sentence
"But in proportion to the unwontedness of such a calamity befalling Lacedaemonians, a widespread mourning fell upon the whole"
"The trees of the fields and plantations writhed like miserable men as the air wound its way swiftly among them: the lowest portions of their trunks, that had hardly ever been known to move, were visibly rocked by the fiercer gusts, distressing the mind by its painful unwontedness, as when a strong man is seen to shed tears."
"Not because of the unwontedness of a return to English scenery; not because he was about to meet his parents, and settle down for awhile to English cottage life."