The state or quality of being apart, separate, or distant; the condition of separation or isolation.
From apart (from Old French a part, meaning 'to the side' or 'separately') + -ness (noun suffix forming abstract nouns). The suffix -ness converts the adjective into a noun describing the quality of being separate.
The word 'apartness' captures something philosophical—it's not just physical distance but the feeling of being set apart, which is why the same word describes both geographical distance and social isolation!
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