Deffier a townland in this Area Drumleague Drumhaver and Cornaroy belonged to the La Touche Estate.
La Touche had his House in the townland of Drumharney beside the present day village of Leitrim.
He was a planter of French extraction but I leave this to the Leitrim Teachers. They know the La Touche Geneoligy I expect.
The first of our townlands on his estate Deffier was originally known as Mullaghnagluck and Mullaghnaguillte. The people today speak of Deffier Upper and Deffier Lower.
Some Irish scholars hold that Deffier means [?] others [?], but the old people of the townland who know no Irish say that La Touche was not able to remember "the cursed Irish names" of Mullaghnagluck and Mullaghnaguillte and so gave the French name Defare or Day-farie which means in French Black Grass. I know no French so make what you like of it. I tell what I heard. I'm giving the phonetic sound of each place name as best I can.
- Seán Ó Céilleachair