The act or state of debauchery; excessive indulgence or corruption of morals.
From 'debosh' plus the suffix '-ment,' creating an abstract noun for the condition or practice of behaving in a debauched manner, following the pattern of '-ment' nominalizations.
Medieval and early modern English had a whole vocabulary of vice and debauchery—'deboshment,' 'drunkenness,' 'licentiousness'—suggesting people were just as fascinated by moral transgression then as now, they just had fancier words for it.
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