RIAL is a 4 letter word that starts with R.

1. \Ri"al\, n.
   A Spanish coin. See {Real}. [Obs.]
   
   

2. \Ri*al"\, a.
   Royal. [Obs.] --Chaucer.
   
   

3. \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.