# Esperanto nouns and adjectives: -o, -a and plural -j

Source: https://esperantopedia.org/grammar/nouns-adjectives/
Language: en
Updated: 2026-10-07

> Esperanto nouns end in -o and adjectives in -a; both add -j for plural and -n for object: bonajn katojn. Agreement, comparison with pli and plej.

Every Esperanto noun ends in *-o* and every adjective in *-a*. Both add *-j* for the plural and *-n* for the object, and an adjective always matches its noun: *bona kato*, *bonaj katoj*, *bonan katon*, *bonajn katojn* – "good cat(s)". There is no grammatical gender and no irregular plural.

## Nouns: the -o ending

A noun is any word ending in *-o*: *domo* – "house", *amiko* – "friend", *kuro* – "a run". The ending shows the word class, so one root gives several words: *bela* – "beautiful", *bele* – "beautifully", *belo* – "beauty". This is the basis of Esperanto [word building](https://esperantopedia.org/grammar/word-building/).

Nouns have no grammatical gender. Most words for people, like *amiko* – "friend" or *instruisto* – "teacher", say nothing about sex. A few roots are male by meaning, and the suffix *-in-* makes the female form: *patro* – "father", *patrino* – "mother". See [suffixes](https://esperantopedia.org/grammar/suffixes/).

## The plural: -j

Add *-j* after the ending: *domo* → *domoj* – "houses", *bela* → *belaj*. The ending *-oj* sounds like "oy" in "boy", and *-aj* like "eye".

After any number above one, the noun is plural: *du katoj* – "two cats", *tri grandaj domoj* – "three big houses". With *unu* – "one", it stays singular: *unu tago* – "one day".

## Agreement: the adjective copies its noun

An adjective takes the same *-j* and *-n* as the noun it describes. This is the complete pattern:

| | Singular | Plural |
|---|---|---|
| **Subject** | *bona kato* | *bonaj katoj* |
| **Object (-n)** | *bonan katon* | *bonajn katojn* |

- *La bonaj katoj dormas.* – "The good cats are sleeping."
- *Mi vidas bonajn katojn.* – "I see good cats."

The order never changes: ending, then *-j*, then *-n*. So *katojn*, never *katonj*. The plural object ending *-ojn* rhymes with English "coin". When to add *-n* is explained on [the accusative](https://esperantopedia.org/grammar/accusative/).

Words that work like adjectives agree in the same way. This includes possessives such as *mia* – "my" and correlatives such as *tiu* – "that": *miajn amikojn* – "my friends" (object), *tiujn librojn* – "those books" (object). See [pronouns](https://esperantopedia.org/grammar/pronouns/) and [correlatives](https://esperantopedia.org/grammar/correlatives/).

### Position of the adjective

The adjective usually comes before the noun, but after the noun is also correct: *bela domo* or *domo bela* – "a beautiful house". The endings show which noun it belongs to, even when the word order changes.

### Adjectives after esti

After *esti* – "to be", *iĝi* – "to become" and *ŝajni* – "to seem", the adjective agrees in number but never takes *-n*:

- *La katoj estas bonaj.* – "The cats are good."
- *La domo ŝajnas malnova.* – "The house seems old."

One adjective describing two singular nouns joined by *kaj* – "and" is plural: *La tablo kaj la seĝo estas novaj.* – "The table and the chair are new."

## Comparison: pli, plej, ol

Esperanto has no comparative endings and no irregular forms like "good – better – best". Short words do the job:

| Meaning | Pattern | Example | Translation |
|---|---|---|---|
| more … than | *pli … ol* | *Paŭlo estas pli alta ol Petro.* | "Paul is taller than Peter." |
| less … than | *malpli … ol* | *Teo estas malpli forta ol kafo.* | "Tea is less strong than coffee." |
| the most | *la plej … el* | *la plej bona el ĉiuj* | "the best of all" |
| the least | *la malplej* | *la malplej multekosta* | "the least expensive" |
| as … as | *tiel … kiel* | *tiel granda kiel vi* | "as big as you" |
| just as | *same … kiel* | *same alta kiel mi* | "just as tall as me" |

*Bona* stays regular: *pli bona* – "better", *la plej bona* – "the best". The same words compare adverbs: *pli rapide* – "faster".

After *ol* and *kiel*, a word keeps the role it would have in the full sentence:

- *Mi amas vin pli ol li.* – "I love you more than he does."
- *Mi amas vin pli ol lin.* – "I love you more than (I love) him."

For "very" and "too", use *tre* and *tro*: *tre granda* – "very big", *tro granda* – "too big". The suffixes *-eg-* and *-et-* change strength inside the word: *granda* → *grandega* – "huge", *domo* → *dometo* – "cottage".

## Common mistakes

| Wrong | Right | Why |
|---|---|---|
| *bona katoj* | *bonaj katoj* | The adjective copies the plural. |
| *Mi havas du kato.* | *Mi havas du katojn.* | Plural after numbers above one, plus *-n* for the object. |
| *katonj* | *katojn* | *-j* always comes before *-n*. |
| *La katoj estas bonajn.* | *La katoj estas bonaj.* | No *-n* after *esti*. |
| *pli bona ke vi* | *pli bona ol vi* | "Than" is *ol*. |

## Common questions

### Do Esperanto adjectives agree with nouns?
Yes, in number and case. If the noun has *-j* or *-n*, so does every adjective describing it: *grandajn domojn* – "big houses" (object). There is no gender agreement, because there is no grammatical gender.

### How do you form the plural in Esperanto?
Add *-j* to the noun and to its adjectives: *nova libro* → *novaj libroj* – "new books". There are no exceptions.

### How do you say "better" and "best" in Esperanto?
*Pli bona* is "better" and *la plej bona* is "the best". For adverbs: *pli bone* – "better", *plej bone* – "best".

### Can an adjective come after the noun?
Yes. *Domo bela* and *bela domo* are both correct; the endings show which words belong together.

## Sources

- [Fundamento de Esperanto, rules 2 and 3 (English)](https://www.akademio-de-esperanto.org/fundamento/gramatiko_angla.html) – Akademio de Esperanto
- [Seksa signifo de O-vortoj](https://bertilow.com/pmeg/gramatiko/o-vortoj/seksa_signifo.html) – PMEG
- [A-vortoj: bazaj reguloj](https://bertilow.com/pmeg/gramatiko/a-vortoj/bazaj_reguloj.html) – PMEG
- [Nombro: bazaj reguloj](https://bertilow.com/pmeg/gramatiko/unu-nombro_multe-nombro/bazaj_reguloj.html) and [Nombro ĉe A-vortoj](https://bertilow.com/pmeg/gramatiko/unu-nombro_multe-nombro/uzado/a-vortoj.html) – PMEG
- [N-finaĵo: bazaj reguloj](https://bertilow.com/pmeg/gramatiko/rolmontriloj/n/bazaj_reguloj.html) – PMEG
- [Kiel kaj ol: uzado](https://bertilow.com/pmeg/gramatiko/komparoj/kiel_ol/uzado.html) and [kun rolmontriloj](https://bertilow.com/pmeg/gramatiko/komparoj/kiel_ol/kun_rolmontriloj.html) – PMEG
- [Esperanto grammar](https://en.wikipedia.org/wiki/Esperanto_grammar) – Wikipedia