The quality or degree of being fake, false, or unconvincing.
From 'faky' (adjective meaning fake-like) plus the suffix '-ness' (which creates nouns from adjectives). This is a productive English word formation pattern.
Although it's grammatically perfect English, 'fakiness' is rarely used because we prefer established words like 'artificiality' or 'falseness'—it shows how English has multiple ways to say the same thing.
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