Tristernagh Abbey (Irish: Mainistir Thriostarnaí, IPA: ˈmˠanʲəʃtʲəɾʲˈhɾʲɪsˠt̪ˠəɾˠn̪ˠiː), also known as the Priory of Kilbixy or Kilbisky, Tristernagh Priory, or the priory of the Blessed Virgin Mary of Tristernagh, is a ruined Augustinian monastery in the townland of Tristernagh in the barony of Kilbixy in County Westmeath, Ireland. It is situated on the shores of Lough Iron, about 3 kilometres (1.9 mi) north east of the village of Ballynacargy. The name "Tristernagh" comes from the Irish triostarnach, "place of thorns".