The Welsh word for twenty is ugain – although it’s technically not the only one, with the alternative dau ddeg (literally two tens) becoming more and more common.
Still, ugain is very idiomatic and has a long history of being used in the Welsh language, as part of the traditional ugeiniol (vigesimal) counting system, which is arranged around the very number ugain itself.
The plural of ugain is ugeiniau (twenties).
ugain
twenty
ugeiniau
twenties
The plural form ugeiniau may not appear very often, but it can be useful – for example, in the phrase yn ei ugeiniau (“in his twenties”) when referring to age. One situation where it is not useful, however, is when trying to use it to mean ‘scores’ as in English, since this would sound very old-fashioned. This is the case even though ugain could be seen as a translation of ‘score’; in practice, the borrowed word sgôr is preferred.
Unlike almost all words featuring u, the u in the word ugain is generally pronounced the same way in North and South Wales. The letter u, called u bedol (horseshoe ‘u’) is usually pronounced exactly like i in South Wales, but with the tongue placed further back in the mouth in North Wales, producing a unique sound not found in English.
However, in ugain, North and South Walians usually pronounce the initial u the same as i dot (dotted ‘i’), the way that South Walians pronounce all u sounds.
There can still be some variations in how the word is said – some South Walians extend the initial vowel to make it longer, like the i in tri (three) rather than the i in dim (nothing). Length is a pretty normal variation in all vowel sounds in Welsh. Also, people from all over the country may condense the second syllable slightly, to gyan, gan, or gen.
Dw i’n meddwl ei fod o’n ugain o bunnau.
I think it’s twenty pounds.
Ugain comes from the old Welsh uceint, which evolved from proto-Celtic *wikanti. Though it isn’t a borrowing from Latin, the Latin word viginti originates from the same proto-Indo-European root, meaning similar words appear in many European and even Indian languages.
To actually use this word, you’ll need to know that objects in Welsh works slightly differently than in English. There are two options.
Firstly, you can use the singular form of the noun you’re counting. Say you’re talking about cadeiriau (chairs). You would render twenty apples as ugain cadair, which literally translates to twenty apple.
Secondly, you can use the plural form, but in this case you have to insert the word o (of / from) in between the number and the noun. In this case twenty chairs would be ugain o gadeiriau, which literally means twenty of chairs. It’s important to remember here if using this system that o causes a soft mutation; that’s why cadeiriau has become gadeiriau.
This second system of rhifo is particularly common with larger numbers like ugain.
Mae hi wedi bod yn canu ers (ei) bod hi’n ugain (oed).
She’s been singing since she was twenty.
I mentioned that Welsh has two counting systems – the first of which is all about ugain.
The ugeiniol counting system works like this: rhifau (numbers) up to deg (ten) have unique enwau (names).
Between deg and pedwar ar ddeg (fourteen), the rhifau less than deg are combined with the number deg to produce translations of un ar ddeg (eleven), deuddeg (twelve), tri / tair ar ddeg (thirteen), pedwar ar ddeg (fourteen).
Between pymtheg (fifteen) and pedwar ar bymtheg (nineteen), instead of deg, the basis becomes pymtheg. Breaking from the pattern, eighteen can alternatively be deunaw (two nines).
From ugain onwards, ugain is now used as the basis. For example:
- un ar hugain (twenty-one, literally one on twenty)
- dau / dwy ar hugain (twenty-two, literally two on twenty),
- pump ar hugain (twenty-five, literally five on twenty)
- deg ar hugain (thirty, literally ten on twenty)
- pedwar ar bymtheg ar hugain (thirty-nine, literally four on fifteen on twenty)
Luckily it doesn’t go on like this forever because the word for forty is deugain (two twenties), sixty is trigain, and eighty is pedwar ugain. This allows you to ‘reset’ the rhifo (counting) and prevent the numbers from getting too long.
There are some historical instances recorded of pump ugain being used to mean a hundred. This is not done today – we just say cant.
Cyfrifais y teisennau, ac roedd ‘na ddau ar hugain.
I counted the cakes, and there were twenty-two.

A fun quirk of this system is how counting works for numbers like pump ar hugain. To translate, for example, twenty-five books, using the traditional ugeiniol system, you can either say pump ar hugain o lyfrau or you can say pump llyfr ar hugain. This is really cool because you’ve said five books on twenty, with the noun inserted into the middle of the number!
Ordinals in the vigesimal system are formatted similarly. So the phrase my twenty-first birthday would traditionally be fy unfed penblwydd ar hugain (literally my first birthday on twenty).
Now, in the examples above, ugain has become hugain. This is called h-prosthesis and it’s a phenomenon in Welsh a bit like mutation, but which happens in very limited contexts. This is one of those contexts! Ar always causes h-prosthesis to ugain, although in most cases in ordinary speech it would instead cause a soft mutation.
Ugain itself also causes nasal mutations to blynedd (year), blwydd (year), and traditionally, diwrnod (day). So twenty years for example is ugain mlynedd. Plus, ugeinfed (twentieth) causes a soft mutation to feminine enwau that follow it.
Dau ddeg pâr o sgidiau? Mae hynny’n ormod o lawer.
Twenty pairs of shoes? That’s way too many.
The alternative counting system also used in modern Welsh is decimal, like English. Here twenty is dau ddeg. All numbers are constructed in the format un deg pump (fifteen, literally one ten five), dau ddeg wyth (twenty-eight, literally two ten eight), saith deg dau (seventy-two, literally seven ten two), and so forth. It can be a bit simpler when you’re first learning, but most Welsh courses actually teach the traditional method instead, as this is generally perceived as more idiomatic.
Both ways to count are perfectly valid, though it’s good to be familiar with both for ease of understanding. My only warning when it comes to dau ddeg instead of ugain for twenty is that you should be careful not to get it confused with deuddeg (twelve in the ugeiniol system).
Interestingly, the twenties as in the degawd (decade) are pretty consistently referred to as y dau ddegau, using the modern, decimal counting system.
Do you prefer counting fesul ugain (in twenties / vigesimally) or yn ddegol (decimally)? Let us know how you rhifo (count) in Welsh!