A person who alienates or transfers property, rights, or affection to another; one who causes estrangement.
From alienate + -or (a suffix forming agent nouns, from Latin). The -or suffix indicates the person performing the action of alienating.
In legal documents from centuries past, you'll find 'alienators' formally named in property transfers—a now-quaint term for someone selling their land, though modern real estate agents never use it.
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