The range, magnitude, or distance over which a thing extends: landowners unaware of the extent of their own holdings. The degree to which a thing extends: prosecuted to the fullest extent of the law. An extensive space or area: an extent of desert. Law A writ allowing a creditor to assume temporary ownership of a debtor's property. Law In Great Britain, a writ allowing a creditor to seize a debtor's property temporarily. Law The seizure in execution of such a writ. Archaic An assessment or valuation, as of land in Britain, especially for taxation.