Cushla is indeed an old irish term of endearment, mo cuisle meaning my darling. The spelling of Cushla seems to be the english translation in more modern times. the words mo cuisle appers in another song called Dan O`Hara..."O Cuishla ghra mo chroi wont you buy a box from me and you`ll have the prayers of Dan from conemara" As far as I know Dan was a poor man who sold boxes of matches, and the meaning of the first line being "O Darling love of my heart.." note the spelling of Cushla is again different, but that is the Irish language for you, donegal irish being spoke different than conemara irish for example. another translation for cushla is beat of my heart coming from Cuisle meaning pulse. Cushla or any other variations has an overall meaning of someone very dear and loved. i called my daughter Cushla for this very reason and also as she would be the beat of my heart and like a pulse you cannot live without! what a beautiful name.