Je cherche l’infinitif de ce verbe dans le dictionnaire.

Because the subject is je (I), so the verb has to be in the 1st person singular of the present tense:

• je cherche = I am looking for / I look for
• tu cherches = you look for
• il/elle cherche = he/she looks for

So je cherche is the correct present-tense form for I.

L’ is just le or la shortened before a vowel sound.

• le infinitif would be awkward and incorrect
• so it becomes l’infinitif

This is called elision. French often shortens articles this way before a vowel or silent h:

• l’école
• l’homme
• l’infinitif

French usually needs an article where English often does not. Here, l’infinitif means the infinitive form.

So French says:

• Je cherche l’infinitif...

where English might simply say:

• I’m looking for the infinitive...

or even just talk about the infinitive form without thinking much about the article.

In French, leaving the article out here would sound unnatural.

De ce verbe means of this verb.

It tells you which infinitive the speaker is looking for:

• l’infinitif = the infinitive
• de ce verbe = of this verb

So together:

• l’infinitif de ce verbe = the infinitive of this verb

French often uses de to link two nouns in this way, where English uses of:

• le nom de la ville = the name of the city
• la couleur de la voiture = the color of the car

Because verbe begins with a consonant sound, v.

French uses:

• ce before masculine singular nouns starting with a consonant sound
• cet before masculine singular nouns starting with a vowel sound or silent h

Examples:

• ce verbe
• ce livre
• cet arbre
• cet homme

So ce verbe is correct.

Because chercher normally takes a direct object.

You chercher quelque chose = look for something.

So:

• Je cherche un mot.
• Je cherche mes clés.
• Je cherche l’infinitif de ce verbe.

No extra preposition is needed between chercher and the thing being looked for.

It means in the dictionary and tells you where the speaker is looking.

So the structure is:

• Je cherche = I’m looking for
• l’infinitif de ce verbe = the infinitive of this verb
• dans le dictionnaire = in the dictionary

French often places this kind of location phrase at the end of the sentence, just as English often does.

Because French usually requires an article before a noun.

So you say:

• dans le dictionnaire = in the dictionary

not:

• dans dictionnaire

Even when English sounds a bit more flexible, French generally wants the article:

• dans la voiture
• sur la table
• à l’école
• dans le dictionnaire

Yes. Literally, chercher means to look for, but in this context, chercher ... dans le dictionnaire naturally corresponds to look up ... in the dictionary.

So this sentence can be understood as:

• I’m looking for the infinitive of this verb in the dictionary
• or more naturally in English, I’m looking up the infinitive of this verb in the dictionary

French does not always use a special verb exactly matching English look up. Often chercher works fine in context.

French strongly prefers the noun + de + noun structure.

So:

• l’infinitif de ce verbe

is the normal French way to say:

• the infinitive of this verb

French can express possession or association with de much more often than English uses ’s.

Yes, and it is very normal French word order.

The sentence is built like this:

• Je cherche = subject + verb
• l’infinitif de ce verbe = direct object
• dans le dictionnaire = place/location phrase

So the order is:

Subject + verb + object + location

That is a very common and natural pattern in French.

A simple pronunciation guide is:

• l’infinitif ≈ lan-fee-nee-teef

A few useful points:

• the l’ links directly to the next word
• French in is a nasal sound, not a clear English in
• the final f in infinitif is pronounced

So it flows roughly as one unit: linfinitif.

Normally, dans le dictionnaire is the safer and more standard choice for in the dictionary.

Using au dictionnaire would usually not be the natural way to express this idea here. A learner should stick with:

• Je cherche l’infinitif de ce verbe dans le dictionnaire.

You could say du verbe only if the context already makes it clear which verb you mean, but ce verbe is more specific: this verb.

Compare:

• de ce verbe = of this verb
• du verbe = of the verb

So ce points directly to a particular verb, perhaps one the speaker is reading or discussing right now.