Basic Adjectives in Welsh

In Brief

Welsh adjectives usually come after the noun: ci mawr means “a big dog,” literally “dog big.” After a feminine singular noun, an adjective normally undergoes soft mutation, so bach becomes fach in cath fach (“a small cat”). A few very common adjectives, including hen, prif, and hoff, come before the noun instead.

Overview

An adjective is a word that describes a person, thing, or place: words such as “big,” “red,” and “old.” The word being described is a noun (a naming word such as “dog,” “book,” or “house”). Welsh uses these two kinds of words much as English does, but their usual order is different. English says “a red book”; Welsh normally says llyfr coch, literally “book red.”

This is an A1 pattern and one of the most useful pieces of Welsh sentence structure to learn early. It lets you build useful phrases from very little vocabulary: tŷ newydd (“a new house”), coffi poeth (“hot coffee”), and plant hapus (“happy children”). The adjective remains after the noun when the whole phrase is definite: y llyfr coch (“the red book”), not an equivalent of English “the red book” with the adjective moved in front.

Word order is only half of the pattern. Welsh nouns have grammatical gender: each noun is treated as masculine or feminine. After a feminine singular noun, the first consonant of a following adjective may change by soft mutation. That is why “a small dog” is ci bach but “a small cat” is cath fach. If gender and mutation are new to you, learn them as part of the whole phrase rather than as an abstract rule on its own.

How It Works

The beginner rule: noun first, adjective second

For most everyday adjectives, use this pattern:

Pattern	Welsh	English
noun + adjective	ci mawr	a big dog
article + noun + adjective	y llyfr coch	the red book
plural noun + adjective	plant hapus	happy children

Welsh has no indefinite article corresponding to English “a” or “an.” Consequently, ci mawr can mean “a big dog” without an extra word. The definite article y/yr/'r (“the”) goes before the complete noun phrase: y ci mawr (“the big dog”).

More than one adjective can follow a noun. In a simple neutral description, place them one after another: tŷ mawr modern (“a large modern house”). Natural adjective order depends partly on meaning and emphasis, just as it does in English, so it is better to notice whole phrases used by fluent speakers than to translate a long English string word for word.

Soft mutation after a feminine singular noun

A mutation is a regular change to the first sound and spelling of a Welsh word. In standard Welsh, an adjective directly following a feminine singular noun normally takes the soft mutation. A masculine singular noun does not trigger this particular change.

Basic adjective	After a masculine noun	After a feminine noun	Meaning
bach	ci bach	cath fach	small
mawr	tŷ mawr	ysgol fawr	big, large
tal	bachgen tal	merch dal	tall
byr	llyfr byr	stori fyr	short
coch	car coch	sgert goch	red

The relevant soft-mutation changes are:

Unmutated	Soft mutation	Example after a feminine noun
b	f	bach → fach: cath fach
c	g	coch → goch: sgert goch
d	dd	du → ddu: cath ddu
g	disappears	glas → las: ffrog las
ll	l	llawn → lawn: basged lawn
m	f	mawr → fawr: ysgol fawr
p	b	pert → bert: merch bert
rh	r	rhad → rad: siaced rad
t	d	tal → dal: merch dal

Words beginning with a vowel or with a consonant not listed above show no visible change: ystafell oer (“a cold room”) and merch hapus (“a happy girl/woman”). The important habit is to ask two questions: “Is the noun feminine and singular?” and “Can the adjective’s first letter mutate?”

Some adjectives also have a special feminine form. A common example is gwyn (“white”), whose feminine form is gwen; after a feminine noun, mutation then gives wen, as in cath wen (“a white cat”). Such forms are best learned as vocabulary. They do not change the core A1 rule.

Plural nouns

The feminine-mutation rule above is specifically about a singular noun. A plural noun does not normally cause the same mutation:

• cath fach — a small cat
• cathod bach — small cats
• merch dal — a tall girl/woman
• merched tal — tall girls/women

In everyday modern Welsh, many adjectives use their basic singular form after a plural noun: ceir coch (“red cars”), plant bach (“small children”). You will also encounter special plural adjective forms such as bychain, cochion, and gleision, particularly in established phrases and more formal or literary usage. Beginners can safely learn the common noun + basic adjective pattern first.

A few adjectives go before the noun

Several frequent adjectives are normally placed before the noun. Three useful A1 examples are:

Adjective	Pattern	Meaning
hen	hen dŷ	an old house
prif	prif ddinas	capital city; chief city
hoff	hoff lyfr	favourite book

A pre-noun adjective can cause soft mutation of the noun that follows it. Thus tŷ becomes dŷ after hen, dinas becomes ddinas after prif, and llyfr becomes lyfr after hoff. This mutation is caused by the word before the noun, not by the noun’s gender.

Do not conclude that any English adjective may be moved before a Welsh noun. These are learned Welsh patterns. For an adjective you have just met, noun + adjective is the safest default unless a reliable dictionary or example shows otherwise.

Descriptions with “is”

An adjective can also describe the subject after a form of “to be.” In a basic present-tense Welsh statement, the common pattern is:

Mae + noun phrase + yn + adjective

Here yn links the subject to its description. Grammatically, this is called predicative use: the adjective forms the descriptive part of a statement rather than sitting directly beside the noun in a noun phrase.

• Mae'r ci yn fawr. — The dog is big.
• Mae'r gath yn fach. — The cat is small.
• Mae'r llyfr yn ddiddorol. — The book is interesting.

Before an adjective, this yn causes a limited soft mutation, commonly changing initial b, c, d, g, m, p, and t. It does so regardless of the subject’s gender. In speech and informal writing, yn contracts after a vowel: Mae e'n dal (“He is tall”). Initial ll and rh normally remain unchanged after this predicative yn: Mae'r car yn rhad (“The car is cheap”).

Keep the two mutation triggers separate:

Situation	Example	Why the adjective changes
adjective directly after a feminine singular noun	cath fach	the feminine singular noun triggers soft mutation
adjective after predicative yn	Mae'r ci yn fach	yn triggers limited soft mutation

The result can look identical, but the grammatical reason is different.

Examples in Context

Welsh	English	Note
Mae ci mawr yn yr ardd.	There is a big dog in the garden.	Usual noun + adjective order
Mae cath fach ar y soffa.	There is a small cat on the sofa.	Feminine cath mutates bach to fach
Dw i'n darllen y llyfr coch.	I am reading the red book.	The article comes before the noun
Mae hi'n gwisgo sgert goch.	She is wearing a red skirt.	Feminine sgert mutates coch to goch
Mae'r ferch dal yn aros yma.	The tall girl is waiting here.	merch and tal are both mutated in this definite phrase
Prynon ni dŷ newydd.	We bought a new house.	Masculine tŷ leaves newydd unchanged
Mae'r plant bach yn chwarae tu allan.	The small children are playing outside.	A plural noun does not trigger feminine adjective mutation
Mae'r coffi yn boeth.	The coffee is hot.	Predicative yn mutates poeth to boeth
Mae'r ystafell yn lân.	The room is clean.	Predicative yn mutates glân by dropping g
Mae'r car yn rhad.	The car is cheap.	rh normally stays unchanged after predicative yn
Mae hon yn ysgol fawr.	This is a large school.	Feminine ysgol mutates mawr to fawr
Dyma brif ddinas y rhanbarth.	This is the region’s main city.	prif precedes and mutates dinas
Dyma fy hoff lyfr.	This is my favourite book.	hoff precedes and mutates llyfr
Maen nhw'n byw mewn hen dŷ.	They live in an old house.	hen precedes and mutates tŷ

Common Mistakes

Copying English adjective order

• Wrong: mawr ci
• Right: ci mawr
• Why: Most Welsh descriptive adjectives follow the noun. Only use adjective + noun when that particular adjective is normally used there, as with hen dŷ.

Forgetting mutation after a feminine singular noun

• Wrong: cath bach
• Right: cath fach
• Why: Cath is feminine and singular, so the following adjective undergoes soft mutation: b becomes f.

Mutating after every noun

• Wrong: ci fawr
• Right: ci mawr
• Why: Ci is masculine. The normal adjective after it does not mutate merely because it follows a noun. Compare feminine ysgol fawr.

Extending the singular rule to a plural

• Wrong: cathod fach
• Right: cathod bach
• Why: The mutation in cath fach is triggered by a feminine singular noun. With plural cathod, the basic adjective is the safe everyday form.

Leaving out predicative yn

• Wrong: Mae'r ci mawr when you mean “The dog is big.”
• Right: Mae'r ci yn fawr.
• Why: Y ci mawr is the noun phrase “the big dog.” To make a complete descriptive statement with mae, use linking yn before the adjective.

Forgetting that a pre-noun adjective can mutate the noun

• Wrong: hen tŷ
• Right: hen dŷ
• Why: Common pre-noun adjectives such as hen, prif, and hoff trigger soft mutation of a following mutable noun.

Usage Notes

Adjective mutation is clear in careful standard Welsh, but natural speech varies by region and speaker. You may hear a mutation omitted, especially where everyday spoken usage is less formal. As a learner, using the standard pattern—cath fach, ysgol fawr, merch dal—gives you a dependable foundation and helps you recognise both careful writing and speech.

Welsh has important regional differences, including alternative verb forms and vocabulary, but the basic noun + adjective order is shared. Spoken forms of mae ... yn commonly contract: mae e'n, mae hi'n, and maen nhw'n. The apostrophe represents the shortened yn; it is not optional decoration.

A dictionary may label a noun masculine or feminine with m and f. Record that label whenever you learn a noun, because gender often cannot be predicted from meaning or spelling. A useful vocabulary entry is not just cath = “cat,” but cath (f), cath fach. This stores gender, word order, and mutation in one memorable unit.

Beyond the Basics / Advanced Use

You do not need to master the points in this section at A1, but they explain forms you will meet later.

Adjective position can sometimes carry a conventional meaning or a change in emphasis. A particularly clear contrast is unig blentyn (“an only child”) versus plentyn unig (“a lonely child”). This is not a licence to move adjectives freely: each established position and meaning must be learned from usage. Literary Welsh also places some adjectives before nouns more readily than ordinary conversation does.

Some adjectives have gendered or plural forms in addition to mutation. Alongside gwyn you may meet feminine gwen and plural gwynion; alongside glas you may meet gles and gleision. The exact choice varies with the adjective, register, and established phrase. Modern everyday Welsh often avoids making every possible distinction, so learn frequent examples rather than trying to invent forms from a single universal ending.

When two or more nouns are described together, or when an adjective is separated from its noun, agreement and mutation can become less straightforward. Formal writing may preserve distinctions that casual speech levels out. At that stage, check an authoritative dictionary or corpus example for the particular adjective.

Adjectives also feed into comparison. Welsh can express “as tall as,” “taller,” and “tallest” with patterns such as mor dal â, an ending in -ach, or constructions with mwy and mwyaf. Common adjectives may be irregular: da (“good”), gwell (“better”), gorau (“best”). Those patterns belong to the later topic of comparatives and superlatives; first make noun position and basic mutation automatic.

Practice Tips

1. Learn nouns and adjectives as paired phrases. Write five masculine/feminine contrasts such as ci bach / cath fach and tŷ mawr / ysgol fawr. Say each pair aloud so mutation becomes a sound pattern, not only a spelling rule.
2. Transform phrases into sentences. Start with y llyfr diddorol (“the interesting book”), then say Mae'r llyfr yn ddiddorol (“The book is interesting”). This trains the difference between an adjective beside a noun and one linked by yn.
3. Mark the trigger, not just the changed letter. When reviewing merch dal, underline merch as the reason for the mutation. For mae'r bachgen yn dal, underline yn. Knowing what triggers the change makes new examples easier to build.

Related Concepts

• Prerequisite: Gender of Nouns — explains why nouns such as cath and ysgol trigger feminine singular patterns.
• Next step: Colours — practises adjective position and mutation with common colour words.
• Next step: Describing People and Appearance — uses adjectives in fuller descriptions of people.
• Later: Comparatives and Superlatives — extends basic adjectives to “as … as,” “more,” and “most” meanings.