Au singulier, cet adjectif ne se prononce pas comme au pluriel.

Au singulier sets the context first: it means in the singular form or when the word is singular.

French often puts this kind of phrase at the beginning of the sentence to frame what follows. In English, we might also do this:

• In the singular, ...
• When singular, ...

So the sentence structure is very natural in French.

Au is the contraction of à + le.

• à le → au

In this sentence, au singulier is a fixed expression meaning in the singular.

You will often see similar expressions:

• au pluriel = in the plural
• au masculin = in the masculine
• au féminin = in the feminine

So this is not a special one-time usage; it is a very common grammatical pattern.

In French, the standard idiomatic expressions are:

• au singulier
• au pluriel

French simply uses à + article here, not en. This is something learners usually just need to memorize as a fixed pattern.

Compare:

• un mot au singulier
• mettre un nom au pluriel

So even if in the singular / in the plural feels like it might translate with en, French prefers au.

Because adjectif begins with a vowel sound.

French uses:

• ce before a masculine singular noun beginning with a consonant sound
  
  • ce livre
• cet before a masculine singular noun beginning with a vowel or mute h
  
  • cet adjectif
  • cet homme
• cette before a feminine singular noun
  
  • cette table

So adjectif is masculine singular and starts with a vowel, which is why cet is required.

Adjectif is a masculine noun in French.

Its forms are:

• singular: un adjectif
• plural: des adjectifs

The feminine-looking idea comes from English intuition, but in French, noun gender must be learned word by word. Here, adjectif is definitely masculine, so the correct demonstrative is cet.

This is the verb se prononcer in the present tense, with negation:

• se prononce = is pronounced / pronounces itself
• ne ... pas = not

So:

• se prononce = is pronounced
• ne se prononce pas = is not pronounced

This is a very common French way to express something like an English passive.

For example:

• Ce mot se prononce comme... = This word is pronounced like...
• Cette lettre ne se prononce pas. = This letter is not pronounced.

So even though it looks reflexive, it often corresponds to English is pronounced.

French often uses a pronominal construction where English would use a passive.

English:

• This adjective is pronounced...

French:

• Cet adjectif se prononce...

This is very normal and common, especially when talking about pronunciation, usage, or general rules.

Other examples:

• Ça se dit comment ? = How is that said?
• Ce mot s'écrit avec un accent. = This word is written with an accent.

So learners should get used to se + verb as a natural way to express general statements.

Standard written French usually forms negation with two parts:

• ne ... pas

So:

• se prononce = is pronounced
• ne se prononce pas = is not pronounced

In everyday spoken French, people very often drop ne:

• Cet adjectif se prononce pas comme au pluriel.

But in careful speech and standard writing, ne ... pas is the correct full form.

Here, comme means like or the same way as.

So:

• ne se prononce pas comme au pluriel

means that the pronunciation in the singular is different from the pronunciation in the plural.

You can see the same use in other sentences:

• Il parle comme son père. = He speaks like his father.
• Ça s'écrit comme ça. = It is written like that.

In this sentence, comme introduces the comparison.

Because the beginning of the sentence already establishes the point of comparison.

The structure is:

• Au singulier, ... pas comme au pluriel

This means:

• in the singular, it is not pronounced as it is in the plural

French often avoids repetition when the meaning is already clear from context.

A fuller but heavier version might be something like:

• Au singulier, cet adjectif ne se prononce pas comme il se prononce au pluriel.

That is grammatical, but less elegant. The original sentence is more natural.

Yes, in a way. Au pluriel means in the plural form or when plural.

French often uses these short grammatical expressions without repeating the noun:

• au singulier
• au pluriel
• au masculin
• au féminin

For example:

• Ce nom est irrégulier au pluriel.
• Cet adjectif change au féminin.

So au pluriel is compact, but completely natural.

A learner often wonders about this because cet changes shape before a vowel.

Cet adjectif is pronounced roughly like:

• set ah-jek-teef

More precisely, the t in cet is pronounced because it is part of the word cet itself. The sequence flows smoothly into adjectif because the next word begins with a vowel sound.

This is one reason French uses cet instead of ce: it sounds smoother before a vowel.

Yes. This sentence uses a very common pattern for talking about language rules:

• Au singulier, ...
• Au pluriel, ...
• Au féminin, ...
• Au masculin, ...

Examples:

• Au féminin, cet adjectif prend un -e.
• Au pluriel, ce nom prend un -x.
• Au masculin, on dit...

So this sentence is useful not just by itself, but as a model for many grammar explanations.

The pattern is:

• Au singulier, [subject] ne se prononce pas comme au pluriel.

Breaking it down:

• Au singulier = context
• cet adjectif = subject
• ne se prononce pas = negative verb phrase
• comme au pluriel = comparison

This kind of structure is common in grammar books and explanations because it is precise and compact. If you understand this pattern, you will recognize many similar French sentences easily.