Douglas Harper's Etymology Dictionary
common in Welsh place names, literally "St. Mary's Church," from Welsh llan "church" (see land (n.)) + Mair "Mary," with lentition of m- to f-.
Wikipedia
Llanfair ( Welsh for "St. Mary's Parish") may refer to:
Usage examples of "llanfair".
His first living was Llandanwg, and not Llanfair, to which he was collated on January 1st, 1705.
Moreover, the above-named Owen Edwards was the rector of Llanfair until his death which took place in 1711.
John Wynne set up a fine stained-glass window at Llanfair church in memory of his illustrious ancestor.
If you come with me to Llanfair you will have to be Gwylim Griffiths, I suppose.
On Mothering Sunday, when all servants are given leave to visit their mothers, or any credible equivalent, he rides on a borrowed pony to Llanfair, with a present of a Simnel cake, baked in the Castle kitchen, and a gift from the Countess.