Both sionnach and madra rua (literally red dog) are listed in the dictionary as the meaning for ‘fox’. Both are correct. The word sionnach (Old Irish sinnach) would be the most usual form in Connacht. Whereas madadh rua / madú rua would be seen in Donegal Irish.
For West Munster, you would mostly see mada rua / madra rua though it’s worth noting that you will see sionnach as well. For example, there are around 83 mentions in Seán a’ Chóta’s Croidhe Cainnte Ciarraighe. As noted above you will see mada instead of madra due to haplology. Thus madra becomes mada rua due to r repeating.
As mentioned, madra rua translates to red dog, and notice how ‘rua’ is used for ‘red’ here instead of ‘dearg’. This makes a lot of sense as ‘rua’ is mostly used for the rusty colour of hair / fur or things that are copper in colour like pingin rua (a cent).
Loisinnán is another word for fox in Old Irish and means ‘white-tipped one’ referencing the white tip on a fox’s tail.
Interesting to note too that Crimthann, Cremthann, Crimthan or Criofan, is a masculine Irish given name meaning fox. There are quite a few kings in Ireland that had this name including Crimthann mac Fidaig, Crimthann Nia Náir and Crimthann Feimin.
As we explore further, we note that there was a fort called Dún Crimthainn in Howth (then written as Benn Étair) constructed by Crimthann Nia Náir (see The Prose Tales in the Rennes Dindshenchas
below, section 30) and is buried there.
A fort which was constructed on Benn Étair (Howth) by
Crimthann son of Lugaid who was also called Nar’s nia i.e.
man, and who reigned thirteen years.
Tis he that went on an adventure from Dún Crimthainn or
from Dál Uisnig, as he himself said, with the witch Nár the
banshee. With her he slept a month and a fortnight. And to
him she gave many treasures including the gilt chariot and the
draughtboard of gold, and Crimthann’s cétach, a beautiful
mantle, and many other treasures also. And afterwards, after his
adventure, he died on Mag Étair and was buried in his fort.
The surname ‘fox’ (Mac an tSionnaigh – literally son of Fox) is a different story.
In Ireland, the surname originates from Tadgh Ó Catharnaigh (O’Kearney). Tadgh was the chief of Tethbae, a confederation of túatha in central Ireland in the Middle Ages, and who was nicknamed “An Sionnach” (the fox). You can find an in-depth piece on the history of that surname on Sionnach Abú’s website, The Origins and History of the Ó Sionnaigh or Fox Family of Ireland.
Examples of sionnach and madra rua in literature and online:
Croidhe Cainnte Ciarraighe (Gaelainn Chorca Dhuibhne / West Munster)
- Chídhinn go minic an sionnach aosta ag súgradh lé n-a coileánaibh tráthnóintidhe bréagtha (pg. 177)
- Brathadóir maith seadh an madra san, féach nár aithnigh sé go raibh sionnach sa chómhgar (pg. 299)
- B’fhuraist aithint gur sionnach a bhí ann (pg. 679)
Dhá Chéad de Cheoltaibh Uladh

Corpas an Fhoclóra
First hits for sionnach (and tsionnaigh, tsionnach, shionnaigh, etc.

Second for mada rua, madra rua, madadh rua etc.

Logainm.ie
- Loch Sionnaigh (Co. Dublin)
- Droimín na Sionnach (Co. Galway)
- Carraig an Mhadra Rua (Co. Kerry)
- Poll an Mhadra Rua (Co. Waterford)
Other references:
Image by Alain Audet from Pixabay
