This site is great! I am looking for the translation for "You and no other" for a posey ring (like a wedding band). They were popular in France several hundred years ago. I would like it in Gaelic. Also, I haven't studied enough, so forgive me, but what is the difference between Gaelic, Old Irish, and Irish. Thanks for any help you can give me!

"Tú féin amháin"

"Gaelic" is the name of the family branch of The Q-Celtic languages.It is a group of languages, there is no one "gaelic".The same way that there is more than one "latin" language and "germanic" language and "slavic" language.
To say a language is "celtic" is one thing, but to say it's "gaelic" is more specific and synoynmous with calling it a Q-Celtic language.The other branch being "Bretonic" or P-Celtic languages.There are three Gaelic languages, Gaeilge(Irish), Gaidhlig(Scots-Gaelic) and Manannais(Manx).

"Old Irish" is the irish that was spoken in Ireland and then put into written form, by christian monks who came to Ireland, around the collapse of the Roman empire(4th to 5th century).It was the written standard based on the venacular, but the venacular evolved and changed, as languages do and the written form became archaic and was used only by the learned and academics for centuries.The usage of this old vernacular for writing finished with the collapse of irish monasticism with the extensive Viking raids from 795 AD onwards, on the rich monasteries and houses of learning.From this point on, writing returned to the spoken venacular and the authority in the irish language as then written, passed from the monks to the newly enhanced bardic class.

"Irish" is the name given to the irish-gaelic language as spoken today.Referred to, academically, as "Nua-Ghaeilge"(Modern/New Irish)

Thanks for helping me out!!!!