In English law. This was originally a tax or tribute, levied at ln-tervals by act of parliament, consisting of one-fifteenth of all the movable property of the subject or personalty in every city, town-ship, nnd borough. Under Edward III., the taxable property was assessed, and the value of its fifteenth part (then about £29,000) was recorded in the exchequer, whence the tax, levied dn that valuation, continued to be called a “fifteenth,” although, as the wealth of the kingdom increased, the name ceased to be an accurate designation of the propor-tion of the tax to the value taxed. See 1 Bl. Comm. 309
Source: Black’s Law Dictionary 2nd Ed (1910)
