A rare form referring to the quality of being ephemeral; the state of lasting only a short time or being temporary.
From emphemeral (variant of ephemeral, from Greek ephemeros 'lasting only a day') + -ness. The 'em-' prefix variant emphasizes the intensive sense of something fleeting.
Some words add prefixes just for emphasis (like emphemeral for ephemeral), showing how speakers sometimes overcomplicate language when the simple version already says everything.
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