La hundido kaj katido estas similaj.

Hundido is built from hundo = dog plus the suffix -id-, which means offspring, young one, or child of. So hundido means puppy.

This suffix is very common in Esperanto:

• kato = cat → katido = kitten
• bovo = ox/cow → bovido = calf

So when you see -id-, think young one of that animal or parent.

Yes. Katido comes from kato = cat plus -id-. So it means kitten.

That parallel structure is one of the nice things about Esperanto: once you know the parts, many words become easy to understand.

A single la can cover both nouns when they are joined by kaj = and. So La hundido kaj katido means the puppy and the kitten.

You can also say La hundido kaj la katido. That is also correct. Repeating la can sound a little more explicit, but the version with one la is completely normal.

Each noun is singular because each one refers to one animal:

• hundido = one puppy
• katido = one kitten

But together, joined by kaj, they make a plural subject: the puppy and the kitten. So the whole subject is plural even though the individual nouns are singular.

The -j marks the plural. In Esperanto, adjectives agree with the nouns they describe in number.

Here, the subject is plural: La hundido kaj katido. Because of that, the adjective must also be plural:

• singular: simila = similar
• plural: similaj = similar

So estas similaj means are similar.

Because Esperanto verbs do not change according to person or number. Estas is used for:

• I am
• you are
• he is
• they are

So:

• La hundido estas simila. = The puppy is similar.
• La hundido kaj katido estas similaj. = The puppy and kitten are similar.

The verb stays estas in both cases.

Because simila is an adjective, not a finite verb. Esperanto often uses esti + adjective, just like English uses to be + adjective.

So:

• simila = similar
• estas simila/similaj = is/are similar

This works very much like English:

• The puppy is small
• La hundido estas malgranda

Yes, absolutely. That sentence is fully correct.

The version with one la is just a bit more compact:

• La hundido kaj katido estas similaj
• La hundido kaj la katido estas similaj

Both mean the same thing here.

Because there is no direct object here. La hundido kaj katido is the subject, and similaj is a predicate adjective after estas.

In Esperanto, -n is usually used for a direct object or for certain expressions of direction. Neither of those applies here, so no -n is needed.

A rough English-friendly pronunciation is:

lah hoon-DEE-doh kai kah-TEE-doh ES-tahs see-MEE-lie

A few helpful points:

• Stress is always on the second-to-last syllable:
  • hunDIdo
  • kaTIdo
  • EStas
  • siMIlaj
• j is like English y
• aj sounds roughly like eye
• u sounds like oo in food

So similaj sounds roughly like see-MEE-lie.

Usually, yes—that is the natural interpretation. In normal context, La hundido kaj katido estas similaj will usually be understood as the puppy and the kitten are similar to each other.

If you want to be extra explicit, Esperanto can add more words to make that relationship clearer, but the simple sentence already works well in ordinary use.