Irish and Welsh are both Celtic languages, but they belong to different groups. Irish is categorized under the Goidelic group and has nearly 2 million speakers concentrated in the Republic of Ireland, while Welsh belongs to the Brythonic group and has approximately 1 million speakers mainly located in Wales.
Below is a table that compares basic Irish and Welsh vocabulary words side by side. These two languages exhibit significant differences in their fundamental lexicon.
| 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 are 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 into 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 that 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 that 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 the letter ‘c’ while the corresponding Welsh word has the 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) |
The vocabulary of Irish and Welsh exhibits significant differences, to the extent that even cognate words - those that have a common origin - can be challenging to identify without a thorough understanding of the linguistic transformations that took place 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.