1530s, "sufficient estate," from Anglo-French asetz (singular), from Old French assez "sufficiency, satisfaction; compensation," noun use of adverb meaning "enough, sufficiently; very much, a great deal," from Vulgar Latin
Beginning as a legal term, "sufficient estate" (to satisfy debts and legacies), it passed into general use; meaning "any property that theoretically can be converted to ready money" is from 1580s. Asset is a 19c. artificial singular. Asset stripping attested from 1972.