The quality or state of being temporary and short-lived; the characteristic of lasting only a very brief time.
From ephemeral plus the nominal suffix -ness, which creates nouns indicating qualities or conditions (alternative to -ity).
English gives us both 'ephemerality' and 'ephemeralness'—two ways to say the same thing—showing how our language built multiple pathways to express our deep fascination with impermanence.
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