The quality or state of being accountable; the condition of being responsible and answerable for one's actions.
From accountable + -ness suffix. Accountable itself comes from Old French acount (account) + -able (capable of). The -ness suffix creates an abstract noun expressing the quality.
This word peaked in usage during the Victorian era when philosophers and moralists were obsessed with defining personal responsibility—you'll find it throughout 19th-century philosophy texts.
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