Irish and Welsh are the two most spoken Celtic languages. Irish has nearly 2 million speakers most of whom are in the republic of Ireland. Welsh has around 1 million speakers and a majority of them are in Wales.
Irish and Welsh have many more speakers than the other Celtic languages. Breton, the third most spoken Celtic language, has only 200 thousand speakers.
Although Irish and Welsh are both Celtic languages, they belong to different groups of Celtic languages. Irish is in the Goidelic group, whereas Welsh is in the Brythonic group.
The table below provides a side-by-side comparison of some basic Irish and Welsh vocabulary words. This shows how Irish and Welsh differ greatly in their basic vocabulary.
| Irish | Welsh | English |
|---|---|---|
| teanga | iaith | language |
| grá | cariad | love |
| sonas | hapusrwydd | happiness |
| cara | ffrind | friend |
| gealach | lleuad | moon |
| grian | haul | sun |
| abhainn | afon | river |
| sliabh | mynydd | mountain |
| báisteach | glaw | rain |
| baile | tref | town |
The significant differences in vocabulary between Welsh and Irish is due to these languages belonging to different groups among the Celtic languages (Brythonic vs Goidelic). Languages within the same group tend to have more vocabulary similarities.
For instance, « cariad », the Welsh word for “love”, is very different from the corresponding Irish word, « grá ». But the word « cariad » is similar to the Breton verb « karout » which means “to love” (Welsh and Breton are both in the Brythonic group of Celtic languages).
In addition, the Irish word « grá » is similar to the Scottish Gaelic term « gràdh » which also means “love”. (Irish and Scottish Gaelic are both in the Goidelic group of Celtic languages)
In the table below are some Irish and Welsh vocabulary words which are similar. Most of these are cognates, which is a linguistic term referring to words from different languages which have a common origin.
| Irish | Welsh | English |
|---|---|---|
| milis | melys | sweet |
| dorn | dwrn | fist |
| carraig | carreg / craig | rock |
| dubh | du | black |
| neart | nerth | strength |
| garbh | garw | rough |
| lán | llawn | full |
| tine | tân | fire |
| cluas | clust | ear |
| lámh | llaw | hand |
| bolg | bol | stomach |
Some linguists classify Celtic languages in two groups: the P-Celtic languages (which include Welsh) and Q-Celtic languages (which include Irish).
This classification has to do with a particular sound change which occurred as the Celtic languages evolved from the Proto-Celtic language. (The Proto-Celtic language is the ancestor of all Celtic languages. It is a language which has been reconstructed by linguists.)
The Proto-Celtic phoneme kʷ generally evolved into a ‘p’ sound among the P-Celtic languages. And it often evolved into a ‘q’ sound among the Q-Celtic languages.
This explains why many Irish words have a letter ‘c’ while the corresponding Welsh word has a letter ‘p’ instead. Some examples are listed in the table below:
| Irish | Welsh | Proto-Celtic |
|---|---|---|
| ceathair (four) |
pedwar (four) |
*kʷetwares (four) |
| cúig (five) |
pump (five) |
*kʷenkʷe (five) |
| ceann (head) |
pen (head) |
*kʷennom (head) |
| cé (who) |
pwy (who) |
*kʷēs (who) |
| ciall (sense) |
pwyll (sense) |
*kʷēslā (mind, sense) |
| coire (cauldron) |
pair (cauldron) |
*kʷaryos (cauldron) |
| cuid (part) |
peth (thing) |
*kʷezdis (part) |
| cad (what) |
pa (which) |
*kʷid (what) |
| crann (tree) |
pren (tree, wood) |
*kʷresnom (tree, wood) |
| cruimh (worm) |
pryf (worm) |
*kʷrimis (worm) |
| crean (to buy) |
prynu (to buy) |
*kʷrinati (to buy) |
| cré (clay) |
pridd (clay, soil) |
*kʷrīyess (clay) |
| mac (son) |
mab (child) |
*makʷos (son) |
| aitheasc (a speech) |
ateb (answer) |
*sekʷeti (to say) |
| fliuch (wet) |
gwlyb (wet) |
*wlikʷos (wet) |
Many Welsh words start with the letter combination ‘gw’, for instance the popular Welsh name Gwyneth. (for more examples see these articles on Welsh girl names and Welsh boy names)
Many Irish words start with the letter ‘f’, for example the name Fiona which comes from the Irish word « fionn » meaning “fair” or “blond”. (see these articles on Irish girl names and Irish boy names)
The Welsh name Gwyneth and the Irish name Fiona look very different, but they originate from the same Proto-Celtic root.
The Proto-Celtic term « windos » is the origin of the Welsh word « gwyn » which means “white” or “blessed”. It is also the origin of the Irish word « fionn ».
The difference is due to a consonant shift: the letter ‘w’ at the beginning of Proto-Celtic words became ‘gw’ in Welsh, and it became ‘f’ in Irish.
Here are more Welsh and Irish word pairs which illustrate this shift:
| Irish | Welsh | Proto-Celtic |
|---|---|---|
| fear (man, husband) |
gŵr (man, husband) |
*wiros (man, husband) |
| féar (grass) |
gwair (grass) |
*wegrom (grass) |
| fíor (true) |
gwir (true) |
*wīros (true) |
| faoileán (seagull) |
gwylan (seagull) |
*wēlannā (seagull) |
| fleá (feast) |
gwledd (feast) |
*wlidā (feast) |
Irish and Welsh differ greatly in terms of their vocabulary. Even cognate words (words which descend from a common etymological ancestor) are difficult to recognize without in-depth linguistic knowledge of the shifts which occurred as these languages evolved from their Proto-Celtic ancestor.
Welsh is closer to Breton (which is also in the Brythonic group of Celtic languages) than it is to Irish.
Irish is closer to Scottish Gaelic (which is also in the Goidelic group of Celtic languages) than it is to Welsh.
To further compare Welsh and Irish (and to learn some basic phrases in these languages), see these three articles covering Basic Welsh Phrases for Beginners, Welsh compliments, and Irish compliments.
For an overview of Celtic languages, see this article on the easiest and the hardest Celtic languages.