AOISE (pronounced 'Ee sha' is derived from old Irish.
'An t-Aois' in old Irish was a wise person in the community who told people what to do for the future and Aoise is derived from this meaning. It is also where the word 'an tAOISEach' (leader of
Ireland) is derived.
The similarity of 'Aoise' being linked to 'aois' (the modern day Irish word for 'age') is most likely linked to wisdom coming with age and is a modern day and over simplistic meaning