En el diccionario busco un sinónimo de “bonito” y un antónimo de “difícil”.

Yes. Spanish word order is flexible here.

• En el diccionario busco... puts a little more focus on where you am looking.
• Busco... en el diccionario is also completely natural and often feels more neutral.

Both are correct:

• En el diccionario busco un sinónimo...
• Busco un sinónimo... en el diccionario.

Spanish often moves phrases around for emphasis more easily than English.

Because Spanish only makes contractions with a + el = al and de + el = del.

So:

• en + el = en el ✅
• a + el = al ✅
• de + el = del ✅

That is why you say en el diccionario, not a contracted form.

Because Spanish usually drops subject pronouns when they are not needed.

• Busco already means I look for / I am looking for
• The -o ending tells you the subject is yo

So:

• Yo busco = correct, but often unnecessary
• Busco = more natural in many contexts

You would add yo only for emphasis, contrast, or clarity.

It can mean both, depending on context.

In this sentence, busco is in the present tense:

• I look for
• I’m looking for

Spanish present tense often covers both the simple present and the present continuous in English.

If you want to be extra explicit about the action happening right now, you could say:

• Estoy buscando... = I am looking for...

But busco is perfectly normal here.

Because Spanish does not use the continuous form as often as English does.

English often says:

• I’m looking for...

Spanish very often just uses the simple present:

• Busco...

Estoy buscando is possible, but it emphasizes the ongoing action more strongly. In many everyday situations, busco sounds simpler and more natural.

Sinónimo means synonym.

It is masculine because the noun is el sinónimo. So you say:

• un sinónimo
• el sinónimo

Its opposite here is:

• antónimo = antonym

That one is also masculine:

• un antónimo
• el antónimo

There is no special reason you need to memorize beyond learning the noun with its article:

• el sinónimo
• el antónimo

Because in Spanish, sinónimo and antónimo are normally followed by de when you say what word they relate to.

So:

• un sinónimo de bonito
• un antónimo de difícil

This is similar to English a synonym of / for and an antonym of, though Spanish strongly prefers de here.

More examples:

• un sinónimo de rápido
• un antónimo de claro

They can be, and in your model sentence they are shown that way because they are being treated as words themselves.

When talking about a word rather than using it normally, Spanish may use:

• quotation marks
• italics
• sometimes no special marking, depending on the context and style

So these are all possible in practice:

• un sinónimo de bonito
• un sinónimo de “bonito”
• un sinónimo de bonito

The meaning is the same: you are referring to the word bonito itself.

Because the written accent shows where the stress falls:

• di-FÍ-cil

Without the accent, Spanish stress rules would suggest a different pronunciation.

This accent mark is important and must be written:

• difícil ✅
• dificil ❌

Many learners also notice that sinónimo and antónimo have accent marks too:

• si-NÓ-ni-mo
• an-TÓ-ni-mo

In standard Peninsular Spanish, it is approximately:

• dik-thyo-NA-rio in much of Spain

More specifically:

• the c before i is often pronounced like English th in think
• so diccionario sounds roughly like dith-thyo-NA-rio, though the exact sound depends on region and speed

A broad learner-friendly breakdown:

• dic- = like deek but shorter
• cio = roughly thyo
• na-rio = NA-rio

If you use a Latin American s sound instead of the Spain th sound, people will still understand you.

Not exactly. Bonito often means:

• pretty
• nice
• lovely
• sometimes beautiful, depending on context

It is a common, everyday word. It usually sounds a bit less strong or formal than hermoso or bello.

For example:

• un pueblo bonito = a pretty/nice town
• una camisa bonita = a pretty shirt

So bonito is a very useful general adjective.

Because y is the normal Spanish word for and.

So:

• un sinónimo de bonito y un antónimo de difícil

However, Spanish changes y to e before words that begin with an i sound:

• padre e hijo

But here the next word is un, not antónimo, so it stays y:

• ... y un antónimo... ✅

You usually would not in this sentence.

The phrase has two parallel parts:

• un sinónimo de bonito
• un antónimo de difícil

Repeating un makes the structure clear and balanced. It sounds natural.

So this is best:

• Busco un sinónimo de bonito y un antónimo de difícil.

Leaving out the second un would sound less natural to most speakers.

Yes. Bonito is an adjective, so it changes to match gender and number:

• bonito = masculine singular
• bonita = feminine singular
• bonitos = masculine plural
• bonitas = feminine plural

Examples:

• un libro bonito
• una casa bonita
• unos cuadros bonitos
• unas flores bonitas

But in your sentence, bonito is being mentioned as a word, so it stays in its dictionary form.

Because difícil is also being mentioned as a word, not used to describe a noun in the sentence.

Also, difícil has the same form for masculine and feminine singular:

• un examen difícil
• una tarea difícil

Only the plural changes:

• difíciles

In your sentence, it appears in its basic singular form because you are talking about the word itself:

• un antónimo de difícil