Basic Relative Clauses in Welsh

In Brief

To say “the person who is…” or “the thing that does…”, Welsh commonly uses sy or sydd. Before yn, the usual form is sy'n: y dyn sy'n gweithio yma (“the man who works here”). In this pattern, sy/sydd replaces mae; it does not come before it.

Overview

A relative clause is a short clause that identifies or describes a noun (a word for a person, place, thing, or idea). In “the woman who lives next door”, the words in bold tell us which woman we mean. English often introduces this kind of information with who, that, or which.

At A2, the most useful Welsh pattern is a present-tense relative clause with sy or sydd. It builds directly on the present tense of bod (“to be”). Compare Mae'r dyn yn gweithio yma (“The man works here”) with y dyn sy'n gweithio yma (“the man who works here”). The independent clause begins with mae; once it becomes a description attached to y dyn, mae changes to sy/sydd.

This construction is especially common because Welsh often uses bod plus yn to express present actions and states. It lets you talk naturally about people who work somewhere, objects that are in a particular place, buses that go somewhere, or children who are playing.

How It Works

The beginner pattern

Start with an affirmative present-tense sentence containing mae:

Independent sentence	Relative phrase
Mae'r dyn yn gweithio yma. — The man works here.	y dyn sy'n gweithio yma — the man who works here
Mae'r ci yn yr ardd. — The dog is in the garden.	y ci sydd yn yr ardd — the dog that is in the garden
Mae'r plant yn chwarae. — The children are playing.	y plant sy'n chwarae — the children who are playing

The basic transformation is:

noun + mae ... → noun + sy/sydd ...

In other words, do not translate English who/that + is one word at a time. Treat sy/sydd as the special present form that links the description to the noun before it.

Sy, sydd, and sy'n

Sydd is the full form. Sy is its shorter form, and sy'n is the normal contraction of sy + yn.

Form	Typical environment	Example
sy'n	Before the particle yn	y ferch sy'n canu — the girl who is singing
sydd yn	Full form before yn	y ci sydd yn yr ardd — the dog that is in the garden
sydd	Before another word or phrase	y llyfr sydd ar y bwrdd — the book that is on the table
sy	Short form where no yn follows; more frequent in speech and informal writing	y bobl sy yma — the people who are here

For a learner, sy'n before yn and sydd elsewhere are dependable choices. You will also hear and read variation between sy and sydd, but their basic job here is the same.

Be careful with the apostrophe: write sy'n as one unit, not sy yn or sy 'n. The apostrophe shows that part of yn has been omitted.

Why yn sometimes appears and sometimes does not

The word yn has several jobs in Welsh, and this affects what follows sy/sydd.

Present actions

A present action commonly uses yn + verb-noun. A verb-noun is the basic dictionary form used after bod, such as gweithio (“work/working”), chwarae (“play/playing”), or darllen (“read/reading”).

noun + sy'n + verb-noun

• y dyn sy'n gweithio yma — the man who works here
• y plant sy'n chwarae tu allan — the children who are playing outside
• y bws sy'n mynd i'r dref — the bus that goes to town

English may use either a simple present (“who works”) or a continuous form (“who is working”). Welsh can use the same sy'n + verb-noun structure for both, depending on context.

Qualities, roles, and identities

Descriptions with an adjective (a describing word such as “happy”) or a noun used as a role also use yn:

• rhywun sy'n hapus — someone who is happy
• y fenyw sy'n athrawes — the woman who is a teacher
• y dyn sy'n feddyg — the man who is a doctor

After this descriptive yn, some following words undergo soft mutation, a regular change to the first consonant. That is why meddyg appears as feddyg. This mutation belongs to the yn + description pattern, not to sy itself.

Places and other phrases

A location does not always begin with yn. Keep the preposition (a linking word such as “in”, “on”, or “with”) required by the location:

• y ci sydd yn yr ardd — the dog that is in the garden
• y llyfr sydd ar y bwrdd — the book that is on the table
• y bobl sydd gyda ni — the people who are with us
• y siop sydd ger yr orsaf — the shop that is near the station

Do not add yn automatically after sydd. Use it only if the action, description, or location would normally require it after a form of bod.

The noun must be doing or being something

In the basic sy/sydd pattern, the noun being described is the subject of the relative clause—that is, the person or thing doing the action or having the state.

• y bachgen sy'n darllen y llyfr — the boy who is reading the book

Here, y bachgen does the reading, so sy'n is correct.

Now compare:

• y llyfr rydw i'n ei ddarllen — the book that I am reading

Here, I do the reading and the book receives the action. The book is the object (the person or thing affected by the action), so this is not the basic sy/sydd pattern. English uses that in both cases, but Welsh distinguishes them. At A2, first become confident using sy/sydd when the described noun is the one doing or being something.

No repeated pronoun

Because the noun before sy/sydd already supplies the subject, Welsh does not normally repeat it with e, hi, or nhw inside the relative clause:

• y dyn sy'n gweithio yma — literally structured as “the man who works here”
• not y dyn sy mae e'n gweithio yma

This differs from a full sentence such as Mae e'n gweithio yma (“He works here”). When you attach that information to y dyn, both mae and the repeated subject pronoun disappear, and sy'n links the description directly to the noun.

Examples in Context

The following examples show actions, qualities, occupations, and locations. Notice that English who, that, and which all correspond to the same basic Welsh construction when the preceding noun is the subject.

Welsh	English	Note
Dw i'n adnabod y dyn sy'n gweithio yma.	I know the man who works here.	Present action
Dyna'r plant sy'n chwarae yn y parc.	Those are the children who are playing in the park.	Plural subject; sy'n does not change
Mae'r bws sy'n mynd i Fangor yn hwyr.	The bus that goes to Bangor is late.	The bus does the “going”
Prynodd hi ffôn sy'n gweithio'n dda.	She bought a phone that works well.	The main clause is past, but the phone's current property is present
Chwilio am rywun sy'n siarad Cymraeg ydyn ni.	We are looking for someone who speaks Welsh.	A general ability
Y fenyw sy'n athrawes yw Ceri.	The woman who is a teacher is Ceri.	Role introduced with yn
Mae gen i ffrind sy'n hapus i helpu.	I have a friend who is happy to help.	Adjective after yn
Dyma'r ci sydd yn yr ardd.	Here is the dog that is in the garden.	Full sydd yn
Ble mae'r llyfr sydd ar y bwrdd?	Where is the book that is on the table?	ar, so no extra yn
Mae'r siop sydd ger yr orsaf ar agor.	The shop that is near the station is open.	Location with ger
Y bobl sydd gyda ni yw ein cymdogion.	The people who are with us are our neighbours.	Location/company with gyda
Beth yw enw'r gân sy'n chwarae nawr?	What is the name of the song that is playing now?	A thing rather than a person

A relative phrase can sit inside a longer sentence. In Mae'r bws sy'n mynd i Fangor yn hwyr, the words sy'n mynd i Fangor identify the bus, while Mae ... yn hwyr gives the main message about it.

Common Mistakes

Keeping mae after the noun

• Wrong: y dyn mae'n gweithio yma
• Right: y dyn sy'n gweithio yma
• Why: In this affirmative present relative clause, sy replaces mae. The apostrophe belongs to sy'n, the contraction before yn.

Repeating the subject with a pronoun

• Wrong: y plant sy'n nhw'n chwarae
• Right: y plant sy'n chwarae
• Why: Y plant is already the subject of chwarae. Do not add nhw (“they”) inside the clause.

Writing sy yn as two words

• Wrong: y ferch sy yn canu
• Right: y ferch sy'n canu
• Also possible: y ferch sydd yn canu
• Why: The short form before yn is written sy'n. Use sydd yn if you choose the full form.

Adding yn before every location

• Wrong: y llyfr sydd yn ar y bwrdd
• Right: y llyfr sydd ar y bwrdd
• Why: Ar y bwrdd already means “on the table”. There is no reason to insert a second preposition.

Using sy/sydd when the noun receives the action

• Wrong for “the book that I am reading”: y llyfr sy'n darllen
• Right: y llyfr rydw i'n ei ddarllen
• Why: Y llyfr sy'n darllen would make the book the reader: “the book that is reading”. Use a different relative pattern when someone else acts on the noun.

Assuming sy'n always means “is ...-ing”

• Misleading translation: rhywun sy'n siarad Cymraeg = only “someone who is speaking Welsh right now”
• Better: It can also mean “someone who speaks Welsh”.
• Why: Welsh bod + yn + verb-noun covers meanings that English divides between the simple and continuous present. Let the context decide.

Usage Notes

Sy'n is extremely frequent in both speech and writing. Sydd is useful when the next element is not yn, as in sydd ar y bwrdd, and the full sequence sydd yn is also correct. Shorter sy can occur without yn, especially in speech, but learners can safely prefer sydd in careful writing when no contraction is involved.

The form does not agree with number or gender. You use the same sy/sydd after one man, one woman, one object, or several people: y dyn sy'n..., y fenyw sy'n..., y peth sy'n..., y bobl sy'n.... This is simpler than choosing among English who, which, and that.

Relative clauses are often essential for identifying the noun, but Welsh does not place a comma between a noun and a short identifying clause: y trên sy'n mynd i Gaerdydd (“the train that goes to Cardiff”). More loosely added, parenthetical information has its own punctuation and stylistic rules; the comma habits of English should not be transferred automatically.

Beyond the Basics / Advanced Use

You do not need to master the following patterns at A2, but recognising their limits will prevent you from treating sy/sydd as a universal translation of English who or that.

First, sy/sydd is the present affirmative form taught here. Other times and negative clauses use other structures. For example, a more formal negative relative may contain nad: y ferch nad oedd yn hapus (“the girl who was not happy”). In everyday Welsh you may also encounter negative patterns with ddim, but register and tense affect the choice.

Second, when the described noun is an object, a possessor, or follows a preposition, Welsh uses extended relative constructions. Compare the beginner subject pattern y dyn sy'n gweld y car (“the man who sees the car”) with y dyn y gwelais i ei gar (“the man whose car I saw”) and y tŷ y buon ni'n byw ynddo (“the house we used to live in”). These patterns may contain a pronoun or a preposition referring back to the noun. They belong to advanced relative clauses and are best learned as a separate system.

Finally, sy also appears naturally after question words in expressions such as Pwy sy'n siarad? (“Who is speaking?”) and Beth sy'n digwydd? (“What is happening?”). The logic is related: the unknown person or thing is the subject of the action. These very common questions are worth learning as whole phrases even before you study their full grammatical analysis.

Practice Tips

1. Transform mae sentences. Write five sentences such as Mae'r ci yn cysgu (“The dog is sleeping”), then place each after a noun: y ci sy'n cysgu (“the dog that is sleeping”). Cross out mae as you make the change.
2. Sort by what follows. Collect examples in three groups: sy'n + action/description, sydd yn + place, and sydd + another preposition. This trains you to choose y ci sydd yn yr ardd but y llyfr sydd ar y bwrdd.
3. Ask who does the action. Before using sy/sydd, identify the doer. If the noun before the gap does the action, as in “the woman who sings”, the basic pattern fits. If someone acts on that noun, mark the sentence for later study rather than forcing sy'n into it.

Related Concepts

• Prerequisite: Bod — Present Tense — provides the mae + yn patterns that become sy/sydd in a relative clause.
• Next step: Noun Clauses — introduces clauses with bod after verbs such as “think”, “say”, and “know”.
• Later study: Advanced Relative Clauses — covers negative relatives, object and possessive patterns, prepositions, and other tenses.