Cause, Purpose, and Result Clauses in Welsh

In Brief

Use achos, oherwydd (bod), or gan fod to give a reason; use i or er mwyn to state an aim; and use felly, o ganlyniad, or mor ... fel bod to introduce a consequence. English “so” can express either purpose or result, but Welsh normally makes the relationship clearer: er mwyn i ... presents an intended outcome, while fel bod ... often presents the state or consequence that follows.

Overview

A clause is a group of words built around a verb. In “We left because it was late,” we left and because it was late are two clauses. Cause clauses answer “why?”, purpose clauses answer “with what aim?”, and result clauses tell you what followed. These links are essential when you explain a decision, describe a process, or build an argument rather than listing disconnected events.

At B2, choosing the connector matters as much as knowing its dictionary meaning. Spoken Welsh often uses the direct achos (“because”) and felly (“so”), while an explanation in an email, report, or presentation may favour oherwydd bod, gan fod, and o ganlyniad. Purpose also requires attention to sentence structure: a short i phrase is often enough when one person performs both actions, but er mwyn i can introduce a separate subject.

The topic builds directly on Welsh noun clauses with bod (“that; being”). The forms fy mod i, dy fod di, and ei fod e / ei bod hi reappear after gan. If these forms are already familiar, gan fy mod i ... is best learned as “since/because I ...”, not assembled by translating each English word.

How It Works

Cause: achos, oherwydd, and gan fod

The three principal choices overlap, but their structures and tone differ.

Form	What follows	Typical force	Example
achos	a full clause	direct, especially common in conversation	Arhoson ni achos roedd hi'n hwyr.
oherwydd	a noun phrase	because of, owing to	oherwydd y glaw
oherwydd bod	a clause embedded with bod	because; clear in careful speech and writing	oherwydd bod y trên yn hwyr
gan fod	a bod clause	since, as, because; common in connected explanation	gan fod y trên yn hwyr

A noun phrase means a noun together with the words attached to it, such as y tywydd gwael (“the bad weather”). Oherwydd can introduce such a phrase directly:

• Cafodd y gêm ei chanslo oherwydd y tywydd gwael. — “The game was cancelled because of the bad weather.”
• Roedd y ffordd ar gau oherwydd damwain. — “The road was closed because of an accident.”

To give a whole situation as the cause, use oherwydd bod in careful Welsh:

• Oherwydd bod y ffordd ar gau, aethon ni ar hyd ffordd arall. — “Because the road was closed, we took another route.”

With achos, everyday Welsh readily uses a normal finite clause (a clause whose verb shows tense or person), such as mae, roedd, or bydd:

• Alla i ddim dod achos dw i'n gweithio. — “I can't come because I'm working.”

Gan fod and its personal forms

With a noun subject, the pattern is simply gan fod + noun + rest of clause:

• Gan fod y plant yn cysgu, siaradodd pawb yn dawel. — “Since the children were asleep, everyone spoke quietly.”

With a pronoun subject, Welsh uses the same possessive-looking forms found in noun clauses. The changes from bod to mod or fod are mutations—regular changes to the first consonant triggered by the preceding word.

Person	Causal form	Approximate meaning
I	gan fy mod i	since/because I am or was
you, singular informal	gan dy fod di	since/because you are or were
he	gan ei fod e / o	since/because he is or was
she	gan ei bod hi	since/because she is or was
we	gan ein bod ni	since/because we are or were
you, plural or formal	gan eich bod chi	since/because you are or were
they	gan eu bod nhw	since/because they are or were

These forms do not by themselves specify present or past time. The wider sentence and the material following bod supply the intended time and aspect (how an action unfolds or is completed):

• Gan fy mod i'n gweithio heddiw, alla i ddim dod. — “Since I'm working today, I can't come.”
• Gan fy mod i wedi gorffen, es i adref. — “Since I had finished, I went home.”

Do not drop the small word before bod. The full chunk is gan fy mod i, not gan mod i, and gan ei fod e, not gan fod e when the personal pattern is required.

Purpose with i

A purpose is an intended goal; it does not necessarily say that the goal was achieved. When the subject of both actions is the same, Welsh often uses i + verb-noun. A verb-noun is the basic dictionary form used after particles and auxiliary verbs, such as dysgu (“learn/learning”) or prynu (“buy/buying”).

main action + i + mutated verb-noun

• Es i i'r llyfrgell i astudio. — “I went to the library to study.”
• Cododd hi'n gynnar i ddal y trên. — “She got up early to catch the train.”

The i before a verb-noun normally causes soft mutation where the word has one: dysgu → ddysgu, prynu → brynu, gwirio → wirio, gadael → adael. Not every initial consonant changes, so forms such as i astudio remain visibly unchanged.

English also uses “to” for many meanings that are not purpose. In Dw i eisiau mynd (“I want to go”), mynd completes eisiau; it is not an aim introduced by i. Ask whether the phrase answers “What did someone do this in order to achieve?” before treating it as a purpose phrase.

Purpose with er mwyn

Er mwyn + verb-noun means “in order to” and makes intention explicit. It is useful when the purpose is important, when a sentence is long, or when the style is more deliberate.

• Er mwyn dysgu Cymraeg, symudais i Gymru. — “In order to learn Welsh, I moved to Wales.”
• Rhaid arbed ynni er mwyn lleihau costau. — “Energy must be saved in order to reduce costs.”

Notice that the verb-noun directly after er mwyn does not take the mutation caused by a bare i: compare i ddysgu with er mwyn dysgu.

When the person intended to perform the second action is stated separately, use er mwyn i + subject + verb-noun. The verb-noun is normally soft-mutated in this construction:

• Siaradais i'n araf er mwyn i bawb ddeall. — “I spoke slowly so that everyone could understand.”
• Gadawodd hi nodyn er mwyn i ni wybod ble roedd hi. — “She left a note so that we would know where she was.”

This is where English “so that” can mislead. In the examples above, understanding or knowing is the aim. The sentence does not automatically guarantee that everyone understood or that the note was read.

Result with felly and o ganlyniad

Felly links a cause or premise to what follows. It often corresponds to “so” or “therefore” and is natural in both conversation and straightforward writing:

• Roedd y siop ar gau, felly aethon ni adref. — “The shop was closed, so we went home.”

O ganlyniad means “as a result” or “consequently.” It explicitly points back to an earlier event and is especially useful in reports and structured writing:

• Methodd y system. O ganlyniad, collwyd rhywfaint o ddata. — “The system failed. As a result, some data was lost.”

Do not confuse it with o ganlyniad i, “as a result of,” which names the cause immediately afterward:

• O ganlyniad i'r storm, cafodd y gwasanaeth ei atal. — “As a result of the storm, the service was suspended.”

A sentence with felly can also state a conclusion rather than a physical consequence: Mae'r goleuadau i ffwrdd, felly does neb yma (“The lights are off, so nobody is here”). That conclusion may be reasonable without being certain.

Result clauses with mor ... fel bod

To express “so [adjective/adverb] that ...”, Welsh commonly uses:

mor + adjective/adverb + fel bod + result clause

• Roedd hi mor oer fel bod yr afon wedi rhewi. — “It was so cold that the river had frozen.”
• Siaradodd e mor dawel fel bod neb wedi ei glywed. — “He spoke so quietly that nobody heard him.”

Here fel bod embeds a resulting situation. With a pronoun subject, the familiar personal bod pattern can appear where needed, although clauses with a noun subject are often easier to recognise first. The parallel quantity pattern cymaint ... fel bod expresses “so much/many ... that”:

• Roedd cymaint o draffig fel bod y bws awr yn hwyr. — “There was so much traffic that the bus was an hour late.”

Examples in Context

Welsh	English	Note
Alla i ddim aros achos mae rhaid i mi fynd.	I can't stay because I have to go.	Conversational achos + full clause.
Cafodd y daith ei chanslo oherwydd y niwl.	The journey was cancelled because of the fog.	oherwydd + noun phrase.
Oherwydd bod y peiriant wedi torri, bu'n rhaid cau'r siop.	Because the machine had broken down, the shop had to close.	oherwydd bod + complete reason.
Gan fod y plant yn cysgu, diffoddon ni'r teledu.	Since the children were asleep, we turned off the television.	gan fod with a noun subject.
Gan fy mod i'n sâl, es i ddim.	Since I was ill, I didn't go.	First-person gan fy mod i.
Gan ei fod e'n gweithio nos, mae e'n cysgu yn y bore.	Since he works nights, he sleeps in the morning.	Masculine ei fod e.
Agorais i'r ap i wirio'r amserlen.	I opened the app to check the timetable.	Same subject; gwirio → wirio.
Cododd hi'n gynnar i ddal y trên cyntaf.	She got up early to catch the first train.	i marks her purpose.
Er mwyn dysgu Cymraeg, symudais i Gymru.	In order to learn Welsh, I moved to Wales.	Explicit purpose with er mwyn.
Rhoiais i nodyn ar y drws er mwyn i'r postmon wybod ble i adael y parsel.	I put a note on the door so that the postman would know where to leave the parcel.	Purpose with a different stated subject.
Siaradodd yr athrawes yn araf er mwyn i bawb ddeall.	The teacher spoke slowly so that everyone could understand.	Intended outcome, not guaranteed result.
Roedd y trên yn hwyr, felly collon ni ddechrau'r cyfarfod.	The train was late, so we missed the start of the meeting.	Everyday result connector.
Methodd y taliad. O ganlyniad, ni chwblhawyd yr archeb.	The payment failed. As a result, the order was not completed.	More formal linking across sentences.
O ganlyniad i'r eira, roedd yr ysgol ar gau.	As a result of the snow, the school was closed.	o ganlyniad i names the cause.
Roedd hi mor oer fel bod yr afon wedi rhewi.	It was so cold that the river had frozen.	Degree followed by an actual result.
Roedd cymaint o sŵn fel bod neb yn gallu clywed y siaradwr.	There was so much noise that nobody could hear the speaker.	Quantity pattern cymaint ... fel bod.

Common Mistakes

Omitting the personal marker after gan

• Wrong: Gan mod i'n flinedig, es i adref.
• Right: Gan fy mod i'n flinedig, es i adref.
• Why: “Since I am/was” uses the complete form gan fy mod i. The mutation bod → mod is triggered by fy.

Treating oherwydd like conversational achos

• Wrong in careful Welsh: Oherwydd roedd y ffordd ar gau, troeson ni'n ôl.
• Right: Oherwydd bod y ffordd ar gau, troeson ni'n ôl.
• Why: Oherwydd readily takes a noun phrase. Before a whole clause, oherwydd bod is the reliable careful pattern. In informal regional usage you may hear looser clause patterns, but do not make them your default in writing.

Forgetting soft mutation after purpose i

• Wrong: Dw i'n mynd i dysgu Cymraeg.
• Right: Dw i'n mynd i ddysgu Cymraeg.
• Why: Purpose i causes soft mutation: dysgu → ddysgu. Learn the connector and mutated verb-noun as one chunk.

Adding i after er mwyn when there is no subject

• Wrong: Es i i Gymru er mwyn i ddysgu Cymraeg.
• Right: Es i i Gymru er mwyn dysgu Cymraeg.
• Also right: Es i i Gymru i ddysgu Cymraeg.
• Why: Use er mwyn + verb-noun when the subject remains the same. In er mwyn i ..., the i introduces a stated subject: er mwyn i'r plant ddysgu.

Confusing an intention with an actual consequence

• Misleading: Siaradodd hi'n araf fel bod pawb yn deall when you mean only that understanding was her aim.
• Better for purpose: Siaradodd hi'n araf er mwyn i bawb ddeall.
• Better for an observed result: Siaradodd hi mor glir fel bod pawb wedi deall.
• Why: Er mwyn i foregrounds intention. Mor ... fel bod presents what followed as a result.

Leaving out i after o ganlyniad before a cause

• Wrong: O ganlyniad y glaw, cafodd y gêm ei chanslo.
• Right: O ganlyniad i'r glaw, cafodd y gêm ei chanslo.
• Why: Stand-alone o ganlyniad points back to earlier information. Use o ganlyniad i + noun phrase to state the cause directly.

Usage Notes

Register is a tendency, not a rigid rule. Achos is strongly associated with ordinary conversation, but it can appear in informal messages and dialogue. Gan fod and oherwydd bod suit careful explanation and are frequent in writing, yet neither is restricted to formal prose. Felly is broadly useful; o ganlyniad sounds more planned and explicit.

Welsh pronouns vary regionally. After ei fod, “he” may be e in much southern usage and o in much northern usage: gan ei fod e and gan ei fod o have the same structure. Choose a consistent spoken model, but learn to recognise both.

Cause and result can describe the same event from opposite directions. Cafodd y gêm ei chanslo oherwydd y glaw starts with the result and then gives its cause. Roedd hi'n bwrw glaw; felly cafodd y gêm ei chanslo starts with the cause and moves to the result. This change of viewpoint often determines the best connector more reliably than translating English “because” or “so” word for word.

In writing, an introductory reason or purpose clause is commonly followed by a comma, as in Gan fod y swyddfa ar gau, anfonais i e-bost. A short connector inside the sentence may need no break. Punctuation helps the reader, but it does not replace the Welsh clause structure.

Beyond the Basics / Advanced Use

The boundary between purpose and result is not absolute. Fel bod can sometimes mean “so that” when a speaker focuses on arranging a desired state: Rhowch y cadeiriau yma fel bod pawb yn gallu gweld (“Put the chairs here so that everyone can see”). Er mwyn i bawb allu gweld would make the purpose more explicit. Context, intention, and register all influence the choice.

Negative causes often use gan nad ... (“since/because ... not”) rather than trying to insert ddim mechanically into gan fod:

• Gan nad oedd digon o amser, gohiriwyd y drafodaeth. — “Since there was not enough time, the discussion was postponed.”

This pattern draws on negative subordinate clauses and is worth recognising in formal and edited Welsh. Likewise, advanced prose may compress information into noun phrases—oherwydd diffyg amser (“because of a lack of time”)—instead of building a full bod clause. The noun-phrase version is concise; the clause version can state tense, participants, and circumstances more fully.

Result connectors also differ in what they commit the speaker to. Felly can introduce a practical decision (Mae hi'n hwyr, felly awn ni yfory), a logical inference, or a direct consequence. O ganlyniad more strongly frames the second event as an outcome of the first. In careful argument, do not use either connector to disguise a weak causal link: grammar signals the relationship you claim, but it does not prove that the relationship is true.

Finally, several clause patterns can be nested without repeating English structure. For example, Gan fod y trên yn hwyr, ffoniais i'r swyddfa er mwyn iddyn nhw wybod combines cause, main action, and purpose: “Because the train was late, I phoned the office so that they would know.” Build such sentences in layers—reason, action, aim—rather than translating from left to right.

Practice Tips

1. Turn three facts into three viewpoints. Start with Roedd hi'n bwrw glaw. Cafodd y gêm ei chanslo. Rewrite them with oherwydd, felly, and o ganlyniad. Notice which clause comes first and whether you need i.
2. Drill personal gan fod chunks aloud. Cycle through gan fy mod i, gan dy fod di, gan ei fod e / ei bod hi, gan ein bod ni, gan eich bod chi, and gan eu bod nhw with the same ending, such as yn brysur. Whole chunks are easier to retrieve than isolated mutation rules.
3. Test purpose against achievement. For every i or er mwyn sentence, ask whether it states only an aim. Then write a second sentence with felly or mor ... fel bod that states what actually happened.

Related Concepts

• Prerequisite: Noun Clauses — introduces bod and the personal forms fy mod i, ei fod e, and ei bod hi used again after gan.