How to Use ‘Trwy’ in Welsh

Trwy is the Welsh word for ‘through.’ 

While it is generally straightforward compared to other prepositions, it has a few specific uses that have to be learnt. 

Here’s my guide on how to use it correctly!

Conjugation of ‘trwy’

Like many other prepositions, trwy changes its form when combined with personal pronouns.

Here is the conjugation table for trwy:

Note that, like many prepositions, trwy causes a Soft Mutation to the word immediately following it.

• Cymru (Wales) → Trwy Gymru (Through Wales).
• Llythyr (Letter) → Trwy lythyr (By letter).

You will also see the form drwy. This may or may not be a mutation – sometimes, people use drwy even when there is no mutation. This can sound somewhat literary or formal, so it is best practice simply to use trwy when no mutation is needed and drwy otherwise.

Note also the colloquial forms trw and drw. 

Adverbial forms

Much like dros/tros has the adverbial forms drosodd and drosto, so too trwy has the adverbial form trwodd (and drwodd). Sometimes trwyddo/drwyddo are used here, but technically these should be reserved for ‘through him/it’. See the final section of this article for examples of these.

Uses of ‘trwy’ in Welsh

As discussed, the basic meaning of trwy is ‘through’. Generally, any instance of trwy can be translated as ‘through’ in English, and vice versa. It is important, though, to understand exactly when it sounds natural to use trwy. Here are the main use cases:

1. Through (Location/Movement)

The most direct translation of trwy is physical movement ‘through’ a space, opening, or object.

• Aethon nhw trwy’r twnnel. = They went through the tunnel.
• Edrychais i trwy’r ffenest. = I looked through the window.
• Mae’r trên yn mynd trwy Gaerdydd. = The train goes through Cardiff.
• Torrodd e trwy’r dorf. = He broke through the crowd.

2. By means of / By (Method)

This is one of the most useful senses of trwy. When you want to explain how something was done (the method or medium), you can use trwy. Normally we can use ‘through’ in this context in English, too, though we often use ‘by’. 

Do not confuse this ‘by’ with other kinds of ‘by’ which are translated into Welsh using erbyn (by a time) or gan (by a person).

If you are doing something or using a tool/method, use trwy.

• Cysylltwch â ni trwy e-bost. = Contact us by (through) email.
• Dysgu trwy chwarae. = Learning by (through) play.
• Gwnaethon nhw dalu trwy siec. = They paid by (through) cheque.
• Cefais y newyddion trwy lythyr. = I received the news by letter.

Note that for ‘by car,’ ‘by train,’ and so on, Welsh does not use ‘trwy’. Instead, you should use the appropriate preposition, such as ‘mewn car’, ‘ar y trên’, and so on. Unlike many other languages, the Welsh preposition used for transport is usually the same one we use in English – so we say ‘in the car’, ‘on the train’, ‘on the boat’, etc. 

3. Throughout 

This meaning of ‘trwy’ means ‘throughout’ or ‘through the whole of’. It is often used in reference to geographical regions: 

• Mae’r iaith yn cael ei siarad trwy Gymru. = The language is spoken throughout Wales.
• Mae ei gerddoriaeth yn enwog trwy’r byd. = His music is famous throughout the world.

This also applies to other physical things – we can use ‘trwy’r llyfr’ to mean ‘throughout the book’, or ‘trwy’r gân’ to mean ‘throughout the song’, and so on. 

‘Trwy’ can also mean ‘throughout’ a time, which we will take a look at next:

4. Trwy’r dydd/nos/wythnos – All day/night/week etc. 

When referring to a duration of time, trwy is used to say that something happened throughout a certain time. Generally, English uses ‘all’ here.  

• Buon nhw’n siarad trwy’r nos. = They were talking all night (through the night).
• Gweithiodd hi trwy’r dydd. = She worked all day (throughout the day).

We can also add gydol to add a slight emphasis. The effect is a little like ‘through the whole [time]’ or ‘all through the [time]’: 

• Mae’r parc ar agor trwy gydol y flwyddyn. = The park is open all year round (through the whole year; all through the year).

Alternatively, it is possible to add ‘i gyd’ on the end of trwy + [time]. 

• Gweithion nhw trwy’r wythnos i gyd. = They worked through the whole week. 

Note that neither UK English nor Welsh uses ‘through’ in the sense of ‘up to’ as it is used in North America. Instead we should use ‘tan’ (until), ‘hyd’ (to) or ‘hyd at’ (up to):

• Bydda i yma tan fis Mawrth 2027. = I will be here through March 2027.

5. Because of / Due to 

Trwy can also be used to explain the cause of something, often in a negative context, just like the English ‘through negligence’, ‘through lack of…’, ‘through human error’ and so on. 

• Collodd y gêm trwy ddiffyg canolbwyntio. = He lost the game through (due to) a lack of concentration.
• Digwyddodd y ddamwain trwy gamgymeriad. = The accident happened through an error.

Useful Phrases using ‘Trwy’

Trwy’r amser

Meaning: All the time / Constantly

• Mae hi’n cwyno trwy’r amser. = She complains all the time.

Also note the largely Northern form ‘trwy’r adeg’. 

Trwy gyfrwng…

Meaning: Through the medium of…

This is extremely common in Wales regarding education and broadcasting.

• Addysg drwy gyfrwng y Gymraeg. = Welsh-medium education (Education through the medium of Welsh).

Trwodd

Meaning: Through / Throughout / Completed

Just as drosodd is used for ‘over’ without an object, ‘trwodd’ is used for ‘through’ when there is no direct object following it. 

• Wyt ti wedi darllen y llyfr trwodd? = Have you read the book [all the way] through?
• Mae’r dillad yn wlyb domen drwodd. = The clothes are soaking wet through.
• Mae Cymru drwodd i Gwpan y Byd. = Wales are through to the World Cup. 

Trwyddo

In practice, people often use trwyddo to mean ‘through’ in the same circumstances as trwodd above. However, trwyddo should only really be used when there is a sense of ‘through him/it’, or sometimes in set expressions such as ‘trwyddo draw’ meaning ‘through and through’: 

• Mae e’n Gymro drwyddo draw. = He is a Welshman through and through.

Mynd trwy (rhywbeth)

Meaning: To go through / experience / revise

• Mae hi’n mynd trwy gyfnod anodd. = She is going through a difficult period.
• Wnei di fynd trwy’r gwaith eto? = Will you go through (review) the work again?

Trwyadl

Meaning: Thorough / Thoroughly

This is derived from trwy.

• Gwnaethon nhw ymchwiliad trwyadl. = They did a thorough search.

Other phrases 

• mynd trwyddi – to go through it; to go through a lot 
• siarad trwy eich trwyn – to speak through one’s nose 
• rhoi r.y. drwy’r felin – to put someone through it 
• hanner ffordd trwy – halfway through