Cymraeg (Welsh) is a Brythonic Celtic language, meaning it shares less of its vocabulary with English than you’d imagine for two countries right next to each other. However, there are some exceptions to this, like the borrowing clyfar, meaning clever.
clyfar
clever
Obviously, clyfar is a loanword from English, probably borrowed in the mid-1700s. The provenance of clever itself is unclear; it comes from the Middle English cliver, meaning tenacious, but etymologists disagree as to its original root. Some have even suggested it might have been influenced by the Welsh word celfydd, which means talented.
It’s really important in Welsh that any loanwords from English are modified to match Welsh conventions of spelling and pronunciation. This becomes even more important in the modern world where many borrowings are needed to provide vocabulary to describe new technology, like ffôn symudol (mobile phone) or ddyfais electronig (electronic device).
As you can hear above, clyfar sounds different to the English word, and its spelling has been changed to match. (You may come across the alternative spellings clyfer and clefer, but they are falling out of use).
With other loanwords, the form is sometimes changed, such as in the case of -io being added to the ends of verbs that are borrowed so that they appear more like most Welsh verbs. More examples of Celticised borrowings include brecwast (breakfast), licio (to like), and even the rather silly slang word ymeising (amazing).
The mutations of clyfar are as follows:
Soft mutation
glyfar
Nasal mutation
nghlyfar
Aspirate mutation
chlyfar
Clyfar is a feminine singular adjective, and it doesn’t change when describing masculine and plural nouns, probably because it’s an English borrowing – you can always just say clyfar.
Technically, there are also no particular words for as clever as, more clever than, and most clever, as most Welsh adjectives have. Instead, we’d use the terms mor glyfar â, mwy clyfar na, and mwyaf clyfar, respectively. Still, you might sometimes hear people using clyfrach for more clever, as this matches the form most adjectives take.
Rwy eisiau astudio i ddod yn fwy clyfar.
I want to study to become cleverer.
There are a couple of terms derived from clyfar that describe modern technology. For example ffôn clyfar (pl: ffonau clyfar), which means smartphone, and teledu clyfar (pl: teledau clyfar), which means smart TV. Somewhat sadly, though, it’s common to simply use the English word for very recent tech-related vocabulary, especially in more Anglicised parts of Wales. So, slip ffôn clyfar into your next conversation and do your bit to preserve the language!

There is a whole host of synonyms and regional variation when it comes to translating clever into Welsh. Galluog is probably the most proper term to use and will be understood throughout the country – it comes from the verb gallu (can) and has a similar feeling to the English word able. It is also used to mean powerful.
Here are some more common synonyms to make your speech more varied:
- medrus = clever, skilful, intelligent
- deallus = clever, intelligent
- dawnus = wise, gifted
- craff = smart, observant
- hyfedr = a more formal, literary synonym of medrus
- deheuig/dechau = skilful, dextrous
- dethau/deche = Northern and Southern variations of dechau, respectively
- peniog = intelligent
- cofus = wise, having a good memory
If you want to describe an inanimate object as clever, as in a clever device, you can just use clyfar or medrus. So the previous example is dyfais glyfar, and a clever joke would be jôc clyfar.
Merch glyfar iawn wyt ti.
You’re a very clever girl.
Sometimes clyfar, like its equivalent clever, is used more in a sense of dextrous or skilful. If you wanted specifically to describe someone as being clever with their hands, you could say mae’n glyfar â’i ddwylo, mae’n dechau â’i ddwylo, or even just un da ei law yw e (he’s a good-handed one). In this context, Southerners might sometimes also use the slang word cliper, which is another borrowing from English.
Of course, there may be times in life where you want to describe someone who isn’t so clyfar! If you want to be a bit more formal you can say anneallus or di-ddeall (unintelligent), but I’d say the word in most common usage is twp (stupid). Gwirion means silly, and it rhymes with a fairly common Welsh girls’ name – my poor friend Tirion often got called “Tirion wirion” on the playground.
