Peso

The peso (Spanish: "weight") is a unit of currency that originated in Spain and is now used by several former Spanish colonies. The peso coin weighed 27 grams and was of 92 percent pure silver.

Today the term peso is sometimes used interchangeably to include the historic Spanish eight real coin (also called the Spanish dollar or colloquially "pieces of eight"), which was the main Spanish coin during colonial times. This is primarily because pesos were of similar weight and diameter to the eight real coin. However the term peso did not appear on Spanish coinage until 1864, and it is more accurate to refer to the older coinage as the eight real coin (or Spanish dollar, or "pieces of eight").

The peseta is also a unit of currency whose name may be a diminutive of peso.

The pataca is a unit of currency which means peso in Portuguese.

source:
http://en.wikipedia.org/wiki/Peso