Grammar Overview
Overview of Esperanto grammar — the 16 rules, key structures, and links to detailed grammar topics.
Esperanto Grammar in Brief
Esperanto's grammar can be summarized in 16 rules as written by Zamenhof in the original Fundamento de Esperanto (1905). These rules cover the entire grammatical system — there are no exceptions. Mastering these 16 rules gives you full command of Esperanto grammar.
This is not an exaggeration: the 16 rules fit on a single page, and they have remained essentially unchanged for 130 years.
The 16 Rules
Rules 1–5: The Parts of Speech
Rule 1 — Definite Article The definite article is la (the). It is invariable — it never changes for case, gender, or number.
- la libro (the book), la libroj (the books), la bonajn librojn (the good books)
There is no indefinite article. "Un" (a/an) is simply absent:
- libro = a book / the book (context determines)
Rule 2 — Nouns All nouns end in -o. Plural is formed by adding -j. No grammatical gender.
- libro (book), libroj (books), viro (man), virino (woman — using the suffix -in-)
Rule 3 — Adjectives All adjectives end in -a. They agree in number and case with the noun they modify.
- bona libro (good book), bonaj libroj (good books), bonan libron (good book — accusative)
Rule 4 — Numbers Cardinal numbers are invariable. Ordinal adjectives are formed by adding -a.
- unu, du, tri... (1, 2, 3...)
- unua, dua, tria... (1st, 2nd, 3rd...)
Rule 5 — Personal Pronouns
| Pronoun | Meaning |
|---|---|
| mi | I, me |
| vi | you (singular and plural) |
| li | he, him |
| ŝi | she, her |
| ĝi | it |
| si | oneself (reflexive, 3rd person) |
| ni | we, us |
| ili | they, them |
| oni | one, people (impersonal) |
Possessives are formed with the adjective ending: mia (my), via (your), lia (his), etc.
Rules 6–9: Verb System
Rule 6 — Verb Endings Verbs are completely regular — no irregular conjugations whatsoever:
| Ending | Tense/Mood | Example |
|---|---|---|
| -i | Infinitive | paroli (to speak) |
| -as | Present | parolas (speaks/is speaking) |
| -is | Past | parolis (spoke/was speaking) |
| -os | Future | parolos (will speak) |
| -us | Conditional | parolus (would speak) |
| -u | Imperative/Volitional | parolu! (speak!) |
Verbs do not conjugate for person or number. Mi parolas, vi parolas, li parolas, ni parolas — same ending throughout.
Rule 7 — Participles Six participles (3 active + 3 passive):
| Time | Active | Passive |
|---|---|---|
| Present | -anta (speaking) | -ata (being spoken) |
| Past | -inta (having spoken) | -ita (having been spoken) |
| Future | -onta (about to speak) | -ota (about to be spoken) |
These can be used as adjectives (leganta = reading), adverbs (legante = while reading), or combined with esti for compound tenses:
- Mi estas leganta = I am reading
- Mi estis leginta = I had read
- La libro estas legata = The book is being read
Rule 8 — Adverbs Adverbs end in -e and are formed from any root:
- bona (good) → bone (well)
- rapida (fast) → rapide (quickly, rapidly)
- Any verb root + -e is also possible: kure (at a run), laŭte (loudly)
Adverbs do not change for case or number.
Rule 9 — All Words Are Built from Roots + Affixes Any grammatical category can be derived from any root by changing the ending. A single root can function as noun, adjective, adverb, or verb:
- bel- → bela (beautiful adj.), bele (beautifully adv.), belo (beauty n.), beli (to be beautiful v.)
- labor- → labori (to work), laboro (work/labor), labora (working/labor-), labore (laboriously)
Rules 10–14: Syntax and Special Forms
Rule 10 — Accusative Case The accusative (direct object) is formed by adding -n to nouns, pronouns, and adjectives:
- Mi vidas libron. (I see a book.)
- Li amas ŝin. (He loves her.)
- Bonajn librojn mi legis. (Good books I read. — word order flexibility)
The accusative -n also expresses direction of movement (answering "where to?"):
- Mi iras Parizon. (I am going to Paris.)
- Eniru la ĉambron! (Enter the room!)
Rule 11 — Prepositions Esperanto prepositions govern the nominative (no accusative after prepositions, unless direction is implied). Key prepositions:
| Preposition | Meaning |
|---|---|
| al | to, toward |
| de | of, from, by |
| en | in, into |
| el | out of, from |
| sur | on, onto |
| sub | under |
| pri | about, concerning |
| por | for |
| per | by means of, with |
| kun | with (together) |
| sen | without |
| pro | because of, due to |
| dum | during, while |
| antaŭ | before, in front of |
| post | after, behind |
| inter | between, among |
| kontraŭ | against, opposite |
| ĝis | until, up to |
Rule 12 — Yes/No Questions The particle ĉu introduces yes/no questions:
- Ĉu vi parolas Esperanton? (Do you speak Esperanto?)
- Ĉu ne? (Isn't it? / Don't you?)
Rule 13 — Negation Negation uses ne before the verb (or the element being negated):
- Mi ne parolas la francan. (I don't speak French.)
- Ne mi, sed li iris. (Not I but he went.)
Rule 14 — All Words End in a Vowel All Esperanto words (except conjunctions ending in -aŭ and some set expressions) end in a vowel, determined by their grammatical category. This is part of the phonemic regularity.
Rules 15–16: Vocabulary and Borrowing
Rule 15 — Foreign Words International roots are adopted with minimal change:
- teatr+o = teatro (theater)
- telefon+o = telefono (telephone)
- demokrati+o = demokratio (democracy)
Pronunciation follows Esperanto rules. Spelling is adapted to Esperanto phonemics where needed.
Rule 16 — The Separable Compound Element The separating of compound words with a hyphen or the combining them is optional, but roots must remain recognizable. The root -o vs. combining form distinctions are covered in the word-building guide.
Core Grammar Topics
| Topic | Description | Link |
|---|---|---|
| Affixes | All 9 prefixes and 18+ suffixes | Affixes |
| Correlatives | The 45-form table (ki-, ti-, ĉi-, etc.) | Correlatives |
| Verbs | Full verb system, participles, compound tenses | Verbs |
| Nouns | -o ending, article, plural, accusative | Nouns |
| Word Building | Combining roots and affixes | Word Building |
Why Esperanto Grammar Is Different
Compared to natural languages, Esperanto grammar has several unusual properties that make it learnable extremely quickly:
- Zero irregular verbs — The 6 verb endings always work the same way, for every verb, every person, every number.
- No grammatical gender — Nouns are not masculine, feminine, or neuter. Gender words use the -in- suffix for feminine when needed.
- One case marker — Only the accusative (-n) is marked; all other relationships use prepositions.
- Completely predictable word building — Any root + any valid affix combination is grammatical and understandable.
- Separable word class — Any root can be used as noun, adjective, adverb, or verb by changing the ending.
- 16 rules, no exceptions — The Fundamento lists exactly 16 rules. That is the complete grammar.