The quality or state of being fundamentally different or unrelated; lack of similarity or connection.
From disparate + -ness (noun-forming suffix from Old English -nes). The -ness suffix is the most productive way English forms abstract nouns from adjectives (happy → happiness).
The 'disparateness' between your left and right brain hemispheres is fascinating—they process information so differently that neuroscientists have to study them separately, even though they're connected by the corpus callosum!
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