The term 'coin of the REALM' is a phrase used to describe the official currency of a particular country. The crossword solutions for this term are REALM (5 letters), ECU (3 letters), LIRA (4 letters), EURO (4 letters) and PESO (4 letters). The REALM solution refers to the British pound, which is the official currency of the United Kingdom. The ECU solution is an acronym for the European Currency Unit, which was the predecessor to the Euro and was used in the European Union from 1979 to 1999. The LIRA solution refers to the Italian lira, which was the official currency of Italy until 2002. The EURO solution refers to the Euro, which is the official currency of 19 of the 28 countries in the European Union. Finally, the PESO solution refers to the Mexican PESO, which is the official currency of Mexico.