A symmachy is an alliance between two or more cities, often a military alliance.
The term is also associated with a long period of coinage of Epeiros (Epirus) after the demise of Pyrrhos as well as some coinage of Cyrenaica and probably places in addition to the Sicilian ones. Then there are 'league' coinages like Achaean League, Thessalian League, etc. Both appear to imply a coinage that isn't associated with a particular ruler.
PtolemAE
I'm not sure i agree that Symmachy implies coinage not associated with a particular ruler or that it refers to
Epeiros standing alone. I believe that the definition given above of "an
alliance, often a
military alliance" is more accurate.
First, there are several coins that aren't associated with any particular ruler that are not symmachy coins. Look at
Athens owls. Essentially the same coin was issued for a long period of time and was copied by other places as well. The coin isn't associated with any particular ruler, but it it is certainly not a symmachy coin.
Second,
Epeiros was an
area made up of several different groups and tribes that was eventually united into a symmachy. That's why that term is used for that particular issue of coinage.
Symmachy coinage is used to refer to coinage issued by
members of an
alliance.