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Nendrum Monastic Site, County Down


Ir. Aondroim ‘one ridge’


The early monastery whose name is now anglicised as Nendrum stands on Mahee Island in Strangford Lough, now reached over two causeways.  The island bears the name of the founding saint of the monastery.  Mo Chaoi, a pet name for St Caolán, was mentioned in the Tripartite Life of St Patrick (ed. Stokes, p.40), first when the saint met him as a youth, Mochoa, herding pigs (and gave him baptism, tonsure, the gospels and a menistir, as needed by a priest) and later when God provided a crozier, recognising him as a bishop.  A later legend told how Mochaoi stood entranced for 150 years at the angelic song of a bird.  The monastery was an important early foundation, recorded in annal references to abbots, bishops and scribes from AD 496 to 917/74.  Four saints were associated with it in the Martyrology of Donegal: Crónán (Jan. 7), Mochumma (Jan. 31), Mochaoi (June 23), and Cuimmein (July 3), and it was the original centre of the parish of Tullynakill. The Tripartite Life places Mochaoi near Saul in Lecale, and the notes to Oengus’ Calendar of Irish saints locate the monastery in Loch Cuan, Strangford Lough (Féil. Oeng. 158). These notes also speculate on the meaning of the name, whether the island contains one hillock or nine.  Although surviving Irish sources often use the spelling with initial n, possibly originally prefixed by the word ‘in’, it seems the original name of the drumlin site was probably OIr. Oendruim, Mod. Ir. Aondroim meaning ‘one ridge’, as in the verse text of Oengus’ Calendar (June 23rd, p.142):   in sab sochla sona / ó Óendruimm don-rema (‘May the famous happy champion from Óendruim protect us’).  It appears that the Anglo-Normans attempted to revive the monastery in the 12th century.  Reeves found a 13th-century roll which copied charters of John de Courcy in which he granted in 1178 two-thirds of Nendrum to the monks there and in St Mary’s of York (EA 194), and one third to the Bishop of Down; while he gave the monks all of Gillanhari, in Duffren, possibly modern Ballyglighorn on the mainland (EA 191, British Museum Cotton Charters).  A document which claimed to list the Bishop of Down’s see lands in 1210 was probably drawn up in the 15th century, and said that Indrasaig Mac Cahuil, then ruling in Blawico (i.e. in Ui Bhlaithmheic, around Newtownards) gave to the bishop and the Church of Down the island of Nedron, with 4 other islands lying next to it.  Indrasaig also gave the bishop Balledrun, now Ballydrain, with 14 carucates of land.  The 1615 terrier says the Bishop of Down then held ‘Island Magee… three other islands…  Ballyadrean with 14 other towns’, and thus it seems that the 12th-century monastic foundations did not flourish and all the parish had become bishop land (O’Laverty I 366).

The monastery of Antrim was originally called Oentreb, Aontreabh ‘one settlement’ (AD 822-1096), but when the spelling became Aondruim after 1490 (a disputed reference) , the spelling Noendruim for the Down foundation made the N a differentiating feature. It was recorded in ecclesiastical sources from 1179 to 1450 as Neddrum etc., with three islands in Loch Cuan spelled in 1202 as Scatra, Raynche and Crafne, and identified by Reeves as Scatrick, Ranish and Trasnagh (Reeves 1845/1902, 60-68, 16, 67).

However, the site and its original name had been lost, and from the 17th century the island was usually referred to as part of the (Bishop’s) manor of Ballydrain (Reeves 1845/1902, 16-17).  Nevertheless, in 1844 it was rediscovered by Bishop Reeves who, with Guy Stone of Comber, recognised that a ‘lime kiln’ within a circular enclosure on Mahee Island was the round tower of the monastery (UJA ser. 2 viii = Reeves 1845/1902, 17-18).


KM, 2009; McKay, P. (2007): A Dictionary of Ulster Place-Names, p. 115

Additional Information

See the townland of Mahee Island for details of this name

Historical name form

Old FormRef. DateReference

nAondroim an eclipsed form of Aondroim

1999Dict. Ulst. PN 104
Neddrum1222Pontif. Hib. i $152

Aondroma, Criotan, epscop

1630cMart. Don. May 17 p132

Naendroma, Cuimmein, epscop

1630cMart. Don. July 3 p184

Naon dromma i nUltoibh, Mochaoi, abb

1630cMart. Don. June 23 p176

Naondroma, Mochumma, espuc

1630cMart. Don. Jan 31 p32

nAendroma, Cronan Becc, epscop

1630cMart. Don. Jan 7 p8
Castlereagh Lower
Parish in 1851
Mahee Island
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