The poem was a political statement of its' time and was possibly intended as propaganda for Irish culture and nationalism. As times (political and cognominal) changed, the intent of the message was lost and there arose the now commonly held belief that the origins of Gælic names can be located in either Ireland or Scotland by examining the prefixes to the surnames names, viz. O, or M' or Mc or Mac, and variously ascribing different combinations to Ireland, and the others to Scotland, but this has little basis in fact. All are Gælic, and all have been used in Ireland and Scotland, where until 200 years ago, a common language was spoken in both countries. Since that time, the language has sadly declined in usage, and different versions of Gaelic now exist not only those two countries, but different sub-dialects occur in different parts of each. Having said all of that, it must also be said that it would be most surprising to discover a Scot whose name was prefixed by O'.

Mac simply means "son." Mc and M' are abbreviations of Mac.

O' is simply a method of signifying in English, Ó which when used in conjunction with a name, means descendant, and in certain contexts may also mean male grand-child.

In either case, the part of the name following the Ó or the Mac, is the first or given name of an ancestor.

Ó or Ua and Mac are declined thus:
 

The modern collective plural of surnames of these types are formed by prefixing Muinntear, Clann or Síol to the genitive case of the name of the ancestor, while omitting the Ó or the Mac.

Note :

Muinntear	( = muintir = kinfolk, family, people)	causes aspiration;
Clann	( = children, offspring, race)	causes aspiration;
Síol	( = seed, offspring, progeny)	causes eclipsis .