The Collaborative International Dictionary of English v.0.48:

Rial \Ri"al\, n.
   A Spanish coin. See Real. [Obs.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Rial \Ri*al"\, a.
   Royal. [Obs.] --Chaucer.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Rial \Ri"al\, n. [From Royal.]
   A gold coin formerly current in England, of the value of ten
   shillings sterling in the reign of Henry VI., and of fifteen
   shillings in the reign of Elizabeth. [Spelt also ryal.]
   --Brande & C.
   [1913 Webster]

WordNet (r) 3.0 (2006):

rial
    n 1: the basic unit of money in Yemen; equal to 100 fils [syn:
         Yemeni rial, rial]
    2: the basic unit of money in Oman [syn: riyal-omani, Omani
       rial, rial]
    3: the basic unit of money in Iran [syn: Iranian rial, rial]