The quality or state of being accommodable; the capacity to be accommodated or adjusted.
From accommodable plus the suffix -ness, forming an abstract noun. This creates a noun from an already-awkward adjective, compounding the unnaturalness.
This is a word-formation train wreck: take 'accommodate,' add '-able,' then add '-ness' to create a triple-layered word that no English speaker would ever use in conversation or writing.
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