WeeFalorieMan wrote:
I was taught the exact opposite:
Bean means "woman", and
bean also means "wife".
Fear means "man", and
fear also means "husband".
So,
Bean Uí Mhurchú means "wife of
Ó Murchú" and has nothing to do with ownership, just like using the word
fear for "husband" has nothing to do with being owned.
From page 131 of
Teach Yourself Irish (the original version by Dillon and Ó Cróinín):
"A married woman does not take the surname of her husband. If Mary Kelly marries Peter O'Sullivan, she remains
Máire Ní Cheallaigh or may be called
bean Pheadair Uí Shúilleabháin, but not
Máire Ní Shúilleabháin." That's why
Peig Sayers' name, for example, didn't change when she got married. The whole notion of "owning" somebody in marriage is a foreign concept to Gaelic Ireland.

Dia duit, WFM agus Athbhliain faoi shéan is faoi mhaise duit.
Can I say firstly that I have no wish to get into an argument about what was or was not a foreign concept in Gaelic Ireland. Everyone will make his/her own claims regarding that.
My point is a grammatical one - and your own use of 'of' (when you say wife 'of' and husband 'of') above consolidates that point: Uí is the genitive of Ó.
The only difference between your sentence and what I wrote is that you use husband and wife where I used man and woman. I expect that the words husband and wife only came in with Christianity and would submit that Gaelic Ireland was in existence before that. All these are small points in my opinion.
I think that Dillon and Ó Cróinín are trying to ensure that people do not use 'Ní' for a woman's surname after she gets married (assuming she takes her husband's surname). 'Ní' comes from 'iníon' meaning daughter and thus would be totally wrong to use with a spouse's surname. It was and is used with the father's surname. If a woman decides to keep her maiden name after getting married, then of course she would use 'Ní' along with her father's surname - Ní Cheallaigh in the example above. But if she chooses to use her husband's surname she has to use 'Uí' which, like it or not, is the genitive of 'Ó'.