Localize Cy

Localize: Welsh (cy → Cymraeg) — High-Fidelity Skill

Scope & Variants

Welsh (Cymraeg) is the Celtic language of Wales. The default and primary target for product localization is Welsh Standard Written — the unified literary/professional written register used across Wales for government, education, broadcasting, and software UI.

| Locale | Notes | |--------|-------| | cy / cy-GB | Welsh (Wales). Default and primary target. Welsh Standard Written form covers all UI work. | | Northern Welsh (Gogledd) | Colloquial spoken variant — does NOT diverge in written/UI contexts. | | Southern Welsh (De) | Colloquial spoken variant — does NOT diverge in written/UI contexts. |

Practical reality: Welsh has a strong written standard (sometimes called Cymraeg safonol or Cymraeg llenyddol) that is used uniformly across Wales for UI, government, broadcasting, and education. Northern and Southern Welsh diverge in spoken pronunciation, lexicon (e.g., llefrith North vs llaeth South for "milk"), and some verb forms (e.g., dwi'n North vs rwy'n South for "I am"), but these regional differences are largely absent from the written standard used in software localization.

The defining quality concern in Welsh localization is correct application of initial consonant mutations. Mutations are not optional or stylistic — they are mandatory orthographic changes triggered by specific grammatical environments. A Welsh translation with missing or wrong mutations reads as fundamentally broken to a native speaker, even if the rest of the text is correct.

Welsh is a Celtic Brittonic language

Welsh is one of the four surviving Celtic languages, in the Brittonic (Brythonic, P-Celtic) branch:

| Branch | Languages | |--------|-----------| | Brittonic (P-Celtic) — Welsh's family | Welsh (Cymraeg), Cornish (Kernewek), Breton (Brezhoneg) | | Goidelic (Q-Celtic) — DIFFERENT family | Irish (Gaeilge), Scottish Gaelic (Gàidhlig), Manx (Gaelg) |

Welsh shares structural features with Cornish and Breton (mutations, VSO word order, inflected prepositions) but is NOT mutually intelligible with Irish or Scottish Gaelic, despite popular conflation. Calling Welsh "Gaelic" is wrong.

Welsh is also NOT English. Despite Wales sharing the island of Great Britain with England and the deep historical contact between the two languages, Welsh is structurally unrelated to English. Welsh has VSO word order (not SVO), initial consonant mutations (not present in English), inflected prepositions (English has none), and no indefinite article (English has "a/an"). Treating Welsh as "English in disguise" is the most common source of bad Welsh translations.

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Identity Guardrail — Welsh is NOT Gaelic and NOT English

Auto-fail signals (translator is treating Welsh as the wrong language):

| Signal | Diagnosis | Fix | |--------|-----------|-----| | Output uses Sláinte, Slán, Fáilte | Translator wrote Irish, not Welsh | "Welcome" = Croeso; "Goodbye" = Hwyl fawr | | Output uses Gaelic accent marks like à è ì ò ù | Irish/Scottish Gaelic uses grave accents | Welsh uses circumflex (to bach): â ê î ô û ŵ ŷ — never grave | | Output is SVO (subject-verb-object) word order | Translator used English structure | Welsh is VSO — verb first: Cadwodd y defnyddiwr y ffeil | | Output mutations missing or incorrect | Translator skipped Welsh-specific grammar | Apply soft/nasal/aspirate mutation per trigger | | Output uses the before nouns mechanically | English calque | Welsh has only definite article (y/yr/'r) and NO indefinite article | | Output uses of construction (car o John) | English calque | Welsh uses juxtaposition for possession: car John | | Output reads like word-for-word English | English SVO retained | Restructure as VSO with periphrastic bod + yn + verbal noun |

Cultural note: Welsh has Equal Status with English in Wales under the Welsh Language (Wales) Measure 2011. The Welsh Government's strategy Cymraeg 2050 aims for one million Welsh speakers by 2050. The Cymraeg Clir (Plain Welsh) movement promotes accessible, clear Welsh in public communications. Welsh-language-medium contexts (Welsh-medium schools, Welsh-language broadcasting, government bilingual services) are politically and culturally significant. Sloppy or anglicism-heavy Welsh is not just bad style — it is read as disrespect for the language.

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Register Auto-Detection (Apply Before Translating)

Welsh has a T-V distinction:

| Pronoun | Use | Possessive | Verb ending (imperative) | |---------|-----|------------|--------------------------| | chi | Formal singular OR plural (any number) | eich (no mutation) | -wch (Cadwch, Dewiswch) | | ti | Informal singular only | dy (+ soft mutation) | -a / -â (Cadwa, Dewisa) |

Auto-detect from source:

| Source signal | Target register | |---------------|-----------------| | Professional product UI / business / government (DEFAULT) | chi formal — eich, -wch imperatives, native Welsh vocabulary | | Casual app / social / children's software | ti informal — dy + soft mutation, -a imperatives | | Marketing copy (warm but professional) | chi formal — Welsh marketing is typically formal/respectful | | Legal / banking / official | chi formal — never ti for institutional voice |

Hard rule: never mix chi and ti in the same text.

• ✗ Cadwch eich gwaith + Dewisa — mixes chi imperative with ti imperative
• ✗ Gallwch chi newid dy osodiadau — chi verb form with ti possessive

Special UI exception — verbal-noun buttons are register-neutral: Welsh UI buttons use the berfenw (verbal noun) form, which is neither chi nor ti — it's the bare verb form: Cadw, Dileu, Copio, Agor. This is the established Microsoft/Apple/LibreOffice/Welsh Government convention. Button labels do NOT change between chi and ti registers.

| Surface | chi form | ti form | Verbal-noun (buttons) | |---------|----------|---------|-----------------------| | Imperative ("Save!") | Cadwch | Cadwa | — | | Button label | — | — | Cadw | | Possessive ("your file") | eich ffeil | dy ffeil | — | | Instruction in body text | Dewiswch eich ffeil | Dewisa dy ffeil | — |

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Critical Hard Rules (Severity ≥ 2.0 — Auto-Fail If Wrong)

1. Initial Consonant Mutations — THE defining Welsh feature (severity 2.5)

Welsh mutations change the first letter of a word based on the grammatical environment. There are three mutation systems: soft (treiglad meddal), nasal (treiglad trwynol), and aspirate (treiglad llaes). Mutations are not optional; they are part of the word's spelling in that context.

1a. Soft Mutation (Treiglad Meddal) — most common

The soft mutation softens stops to voiced/fricative equivalents:

| Original | Soft mutation | Example trigger | Example | |----------|---------------|-----------------|---------| | c | g | dy (your-ti) | dy gar (your car) ← car | | p | b | i (to) | i Baris ← Paris | | t | d | o (from) | o Ddenmarc ← Tdenmarc... actually: o Denmarc ← Denmarc | | g | (dropped — ∅) | dy (your-ti) | dy ardd ← gardd (your garden) | | b | f | dy (your-ti) | dy frawd ← brawd (your brother) | | d | dd | dy (your-ti) | dy ddrws ← drws (your door) | | m | f | y (fem. art.) | y ferch ← merch (the girl) | | ll | l | dy (your-ti) | dy law ← llaw (your hand) | | rh | r | dy (your-ti) | dy riant ← rhiant (your parent) |

Soft mutation triggers (the most important set to memorize):

| Trigger | Meaning | Example | |---------|---------|---------| | dy | your (ti, informal) | dy gar (your car) | | ei | his | ei dad (his father) | | y / yr / 'r | the (only before feminine singular nouns) | y ferch (the girl) | | i | to | i Gaerdydd (to Cardiff) | | o | from / of | o Lundain (from London) | | am | about, at (time) | am dri (at three) | | ar | on | ar gadair (on a chair) | | at | towards | at Ddi (to you-ti) | | gan | by, with | gan ferch (by a girl) | | heb | without | heb garden (without a garden... actually gardd) | | tan / dan | under, until | dan fwrdd (under a table) | | dros | over, for | dros bonthwy (over a bridge... pont) | | drwy / trwy | through | drwy goeden (through a tree) | | wrth | by, while | wrth gadw (while saving) | | hyd | until | hyd fory (until tomorrow) | | neu | or (sometimes) | A neu B (or; usually no mutation in modern Welsh) | | yn (predicative, before adj./noun) | "is" + complement | Mae'n ddiddorol ← diddorol (it is interesting) | | yn (adverbial, before adj.) | -ly | yn gyflym ← cyflym (quickly) | | dau / dwy | two (m./f.) | dau gi (two dogs); dwy ferch (two girls) | | tri / tair | three (m./f.) | (note: tri takes aspirate, not soft — see below) | | prif | main, chief (precedes noun) | y prif beth (the main thing) ← peth | | hen | old (precedes noun) | hen dŷ (an old house) ← tŷ | | Feminine singular noun → adjective after it | | merch ddal ← tal (a tall girl) | | Object of inflected (conjugated) verb | direct object soft-mutates | Gwelais gi ← ci (I saw a dog) |

1b. Nasal Mutation (Treiglad Trwynol)

The nasal mutation converts stops to their nasal equivalents:

| Original | Nasal mutation | Example trigger | Example | |----------|----------------|-----------------|---------| | c | ngh | fy (my) | fy nghar ← car (my car) | | p | mh | fy (my) | fy mhen ← pen (my head) | | t | nh | fy (my) | fy nhad ← tad (my father) | | g | ng | fy (my) | fy ngardd ← gardd (my garden) | | b | m | fy (my) | fy mrawd ← brawd (my brother) | | d | n | fy (my) | fy nrws ← drws (my door) |

Nasal mutation triggers (only two real triggers):

| Trigger | Meaning | Example | |---------|---------|---------| | fy | my | fy nghar (my car) | | yn (as locative preposition "in") | in [place] | yng Nghaerdydd ← Caerdydd (in Cardiff). Note: yn itself becomes ym before m-/mh-, yng before ng-/ngh-. |

Critical: yn has three different functions and mutations. See §1d below.

1c. Aspirate Mutation (Treiglad Llaes)

The aspirate mutation affects ONLY c, p, t, converting them to fricatives:

| Original | Aspirate mutation | Example trigger | Example | |----------|-------------------|-----------------|---------| | c | ch | ei (her) | ei char ← car (her car) | | p | ph | a (and) | a phleser ← pleser (and pleasure) | | t | th | ei (her) | ei thad ← tad (her father) |

Aspirate mutation triggers:

| Trigger | Meaning | Example | |---------|---------|---------| | ei | her | ei thad (her father) | | a | and | bara chaws ← caws (bread and cheese) | | â | with (instrument) | â chyllell ← cyllell (with a knife) | | gyda | with | gyda phleser (with pleasure) | | tri | three (m.) | tri chi ← ci (three dogs) | | chwe | six | chwe phunt ← punt (six pounds) | | tua | about, approximately | tua thri (about three) |

1d. The Three Faces of yn — Critical Disambiguation

Welsh yn has three completely different uses, each triggering a different mutation (or none):

| Function | Mutation | Example | |----------|----------|---------| | Progressive aspect (before verbal noun) — "is doing" | NO mutation | Mae'n cadw (he/she is saving). NOT Mae'n gadw. | | Adverbial (before adjective, makes -ly) | Soft mutation | yn gyflym (quickly) ← cyflym | | Predicative (before adjective or noun complement) — "is X" | Soft mutation (but NOT on ll-/rh-) | Mae'n ddiddorol (it is interesting) | | Locative preposition (= "in") | Nasal mutation + yn → ym/yng | yng Nghaerdydd (in Cardiff) |

Common mistake: treating progressive yn as if it mutates. Mae'n gadw is WRONG; Mae'n cadw is right. Verbal nouns after progressive yn keep their dictionary form.

1e. Possessive pronoun mutations (memorize this table)

| Possessive | Meaning | Mutation triggered | |------------|---------|---------------------| | fy | my | Nasal (fy nghar, fy mhen, fy nhad, fy ngardd, fy mrawd, fy nrws) | | dy | your (ti, informal sg.) | Soft (dy gar, dy ben, dy dad, dy ardd, dy frawd, dy ddrws) | | ei (masculine) | his | Soft (ei gar, ei ben, ei dad, ei ardd, ei frawd, ei ddrws) | | ei (feminine) | her | Aspirate (ei char, ei phen, ei thad) — only c/p/t mutate | | ein | our | NO mutation (ein car, ein pen, ein tad) — but often + "n" sandhi: ein nardd? No: ein gardd. | | eich | your (chi, formal/plural) | NO mutation (eich car, eich pen, eich tad) | | eu | their | NO mutation (eu car, eu pen, eu tad) |

UI impact: Formal Welsh UI uses eich (no mutation) → simplifies translation. Informal UI uses dy + soft mutation → requires applying soft mutation to every possessed noun.

2. Welsh 29-Letter Alphabet — Digraphs Are Single Letters (severity 2.5)

The Welsh alphabet has 29 letters, including 8 digraphs that are treated as single letters for sorting, hyphenation, and counting:

a, b, c, ch, d, dd, e, f, ff, g, ng, h, i, j, l, ll, m, n, o, p, ph, r, rh, s, t, th, u, w, y

Critical: w and y are VOWELS in Welsh, not consonants. Welsh has 7 vowels: a, e, i, o, u, w, y. This is why words like cwm (valley), crwth (stringed instrument), y (the), bryn (hill) are valid — w and y are vowels carrying the syllable.

Digraph alphabetical order:

| Digraph | Position | Example | |---------|----------|---------| | ch | After c (NOT after h) | cae, ci, ciuto, ch-... | | dd | After d | da, dy, ddim | | ff | After f | ffon, ffeil | | ng | After g (NOT between n and o!) | gan, gardd, ng-... | | ll | After l | lle, llyfr | | ph | After p | (rare outside mutations) | | rh | After r | rhad, rhif | | th | After t | thri, thal |

Critical for sorting: Welsh dictionary order places ng after g, not between n and o. So nofio (to swim) comes BEFORE ngardd (my-garden), not after. Modern Welsh dictionaries follow this convention.

Critical for hyphenation: Never split a digraph. llygoden hyphenates as lly-go-den, never l-lygoden. anghofio hyphenates as ang-hof-io — no, actually an-gho-fio — wait, since ng is one letter, it stays together: a-ngho-fio. (Welsh hyphenation is complex; the rule is "treat digraphs as one letter".)

Critical for character counting: ffon (stick) has 3 letters (ff, o, n), not 4.

3. To Bach (Circumflex) — Long Vowels (severity 2.0)

The to bach ("little roof") is the circumflex accent that marks long vowels in Welsh. It appears on all 7 vowels: â, ê, î, ô, û, ŵ, ŷ.

The to bach is meaning-critical — it distinguishes minimal pairs:

| Without to bach | Meaning | With to bach | Meaning | |-----------------|---------|--------------|---------| | tan | until / fire | tân | fire (clarified) | | gem | gem | gêm | game | | ty | (no meaning alone) | tŷ | house | | dyn | man | dŷn | (different sense) | | llan | parish | llân | full | | gwn | gun / I know (depends) | gŵn | gown / I know (different) | | cyn | before | cŷn | chisel |

Critical: ŵ and ŷ are uniquely Welsh letters. The circumflex on w and y appears in no other major Latin-script language. NEVER strip these to plain w and y — they change meaning.

Common UI words with to bach:

| Welsh | Meaning | |-------|---------| | tŷ

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Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: i18n-agent
• Source: i18n-agent/i18nstack
• License: MIT
• Homepage: https://i18nagent.ai

Install and usage instructions live in the source repository linked above.