Fumo poluas la medion.

In Esperanto, -o is the standard noun ending. So fumo is a noun meaning smoke.

This is one of the most important patterns in Esperanto:

• -o = noun
• -a = adjective
• -e = adverb
• -i = infinitive verb
• -as = present tense verb

So just by seeing fumo, a learner can immediately tell it is a noun.

-as is the present-tense verb ending in Esperanto. So poluas means pollutes or is polluting, depending on context.

The base verb is polui = to pollute. From that, you get:

• polui = to pollute
• poluas = pollutes / is polluting
• poluis = polluted
• poluos = will pollute
• poluus = would pollute

Unlike English, Esperanto does not change the verb depending on the subject. So:

• mi poluas = I pollute
• vi poluas = you pollute
• fumo poluas = smoke pollutes

The verb form stays the same.

There are two things happening here:

1. la is the definite article, meaning the
2. -n on medion marks the direct object

So:

• medio = environment
• la medio = the environment
• la medion = the environment, as the direct object of the verb

In this sentence, fumo is doing the action, and la medion is receiving the action. Smoke pollutes the environment.

The -n ending marks the direct object in Esperanto. That means it shows what is being affected by the verb.

In Fumo poluas la medion:

• fumo = the subject, the thing doing the polluting
• poluas = pollutes
• la medion = the object, the thing being polluted

This -n ending is very important in Esperanto because it makes sentence roles clear, even if the word order changes.

Esperanto uses la for the, but it does not use an indefinite article like a or an.

So:

• fumo can mean smoke in a general sense
• la medio means the environment

In this sentence, fumo is being used generically, like English smoke in the statement Smoke pollutes the environment. English often uses no article for general substances, and Esperanto can do the same.

You could also say La fumo poluas la medion, but that would sound more like the smoke pollutes the environment, referring to some specific smoke.

Yes, fumo is grammatically singular because it ends in -o, not -oj.

But that does not mean it must refer to one separate, countable unit. Esperanto often uses a singular noun for a substance or general concept, just as English does with words like water, air, or smoke.

So fumo here works like a mass noun: smoke in general.

If you wanted the plural, it would be fumoj, but that would only be used in contexts where separate kinds or instances of smoke are meant.

Yes. Because Esperanto marks the direct object with -n, word order is more flexible than in English.

The normal order is:

• Fumo poluas la medion.

But you could also say:

• La medion poluas fumo.

That still means the same thing, because la medion has the -n and is therefore still the object.

Even so, the most neutral and common order is subject – verb – object, so Fumo poluas la medion is the most straightforward version.

In Esperanto, verbs are normally listed in the -i form, which is the infinitive.

So if you see poluas, you can remove the tense ending -as and recognize the verb stem:

• polu- = the stem
• -i = infinitive
• polui = to pollute

This is very regular in Esperanto:

• vidi → vidas
• fari → faras
• skribi → skribas
• polui → poluas

That regularity is one of the easiest parts of Esperanto grammar for English speakers.

A simple pronunciation guide is:

FOO-mo po-LOO-as la meh-dee-ON

A few helpful points:

• u sounds like oo in food
• o is a pure o sound, not the English diphthong in go
• e sounds like e in bet or met
• stress is usually on the second-to-last syllable

So:

• fumo → FOO-mo
• poluas → po-LOO-as
• medion → meh-dee-ON

Notice that poluas has three syllables: po-lu-as.

Grammatically, yes, but it would usually sound less natural in this context.

La medion means the environment, which is the normal way to express this general idea. Without la, medion would mean simply environment as an object, which can sound less specific or less idiomatic here.

So:

• Fumo poluas la medion = the normal sentence
• Fumo poluas medion = grammatical, but less standard for this meaning

In many cases, Esperanto uses la where English also uses the for a general, understood thing such as the environment.

In Esperanto, the subject usually has no special case ending. The object is the one that gets marked, with -n.

So in this sentence:

• fumo has the basic noun form
• medion has the object marker -n

This means Esperanto often marks what is affected rather than what does the action. That is why learners often focus so much on the accusative -n: it carries a lot of grammatical information.