Parts of speech

1 - Articles

There is no indefinite, and only one definite, article, la, for all genders, numbers, and cases.

Indefinite Definite
English A tree The tree
Esperanto Arbo La arbo

2 - Substantives

Substantives are formed by adding o to the root. For the plural, the letter j must be added to the singular. There are two cases: the nominative and the objective (accusative). The root with the added o is the nominative, the objective adds an n after the o.

Root Singular (nominative) Singular (objective) Plural (nominative) Plural (objective)
English Father The father The father The fathers The fathers
Esperanto Patr La patro La patron La patroj La patrojn

Other cases are formed by prepositions; thus, the possessive (genitive) by de, “of”; the dative by al, “to”, the instrumental (ablative) by kun, “with”, or other preposition as the sense demands. E. g. root patr, “father”; la patr’o, “the father”; la patr’o’n, “the father” (objective), de la patr’o, “of the father”; al la patr’o, “to the father”; kun la patr’o, “with the father”; la patr’o’j, “the fathers”; la patr’o’j’n, “the fathers” (obj.), por la patr’o’j, “for the fathers”.

3 - Adjectives

Adjectives are formed by adding “a” to the root. The numbers and cases are the same as in substantives. The comparative degree is formed by prefixing pli (more); the superlative by plej (most). The word “than” is rendered by “ol”, e. g. pli blanka ol neĝo, “whiter than snow”.

Prefix Example
Positive Blanka (White)
Comparative Pli (More) Pli blanka (Whiter)
Superlative Plei (Most) Plei blanka (whitest)
Partcle comparative Ol (than) Pli blanka ol neĝo (Whiter than snow)

4 - Numbers

The cardinal numerals do not change their forms for the different cases.

Numerical Esperanto
1 Unu
2 Du
3 Tri
4 Kvar
5 Kvin
6 Ses
7 Sep
8 Ok
9 Naŭ
10 Dek
100 Cent
1000 Mil

The tens and hundreds are formed by simple junction of the numerals, e.g. 533 = kvin’cent tri’dek tri. Ordinals are formed by adding the adjectival “a” to the cardinals, e.g. unu’a, “first”; du’a, “second”, etc. Multiplicatives (as “threefold”, “fourfold”, etc.) add obl, e.g. tri’obl’a, “threefold”. Fractionals add on, as du’on’o, “a half”;kvar’on’o, “a quarter”. Collective numerals add op, as kvar’op’e, “four together”. Distributive prefix po, e. g., po kvin, “five apiece”. Adverbials take e, e. g., unu’e, “firstly”, etc.

5 - Personal pronouns

The personal pronouns are:

English Esperanto
I Mi
You Vi
He Li
She Ŝi
It Ĝi
Self Si
We Ni
They Ili
One Oni

Possessive pronouns are formed by suffixing to the required personal, the adjectival termination. The declension of the pronouns is identical with that of substantives. E.g. mi, “I”; mi’n, “me” (obj.); mi’a, “my”, “mine”.

6 - Verbs

The verb does not change its form for numbers or persons, e.g. mi far’as, “I do”; la patr’o far’as, “the father does”; ili far’as, “they do”.
Forms of the Verb:

Ending Example
Present tense as Mi faras (I do)
Past tense is Mi faris (I did)
Future tense os Mi faros (I will do)
Subjunctive mood us Mi farus (I may do)
Imperative mood u Mi faru (Let me do)
Infinitive mood i Fari (To do)

There are two forms of the participle in the international language, the changeable or adjectival, and the unchangeable or adverbial.

Ending (adjectival) Ending (adverbial) Examples
Present participle (active) anta ante Faranta (He who is doing), Farante (Doing)
Past participle (active) inta inte Farinta (He who has done), Farinte (Having done)
Future participle (active) onta onte Faronta (He who will do), Faronte (about to do)
Present participle (passive) ata ate Farate (Being done)
Past participle (passive) ita ite Farita (That which has been done), Farite (Having been done)
Future participle (passive) ota ote Farota (That which will be done), Farote (About to be done)

All forms of the passive are rendered by the respective forms of the verb est (to be) and the participle passive of the required verb; the preposition used is de, “by”. E.g. ŝi est’as am’at’a de ĉiu’j, “she is loved by every one”.

7 - Adverbs

Adverbs are formed by adding e to the root. The degrees of comparison are the same as in adjectives, e.g., mi’a frat’o kant’as pli bon’e ol mi, “my brother sings better than I”.

8 - Prepositions

All prepositions govern the nominative case.

General rules


Every word is to be read exactly as written, there are no silent letters.


The accent falls on the last syllable but one, (penultimate).


Compound words are formed by the simple junction of roots, (the principal word standing last), which are written as a single word, but, in elementary works, separated by a small line (‘). Grammatical terminations are considered as independent words. E. g. vapor’ŝip’o, „steamboat” is composed of the roots vapor, „steam”, and ŝip, „a boat”, with the substantival termination o.


If there be one negative in a clause, a second is not admissible.


In phrases answering the question “where?” (meaning direction), the words take the termination of the objective case; e. g. kie’n vi ir’as? “where are you going?”; dom’o’n, “home”; London’o’n, “to London”, etc.


Every preposition in the international language has a definite fixed meaning. If it be necessary to employ some preposition, and it is not quite evident from the sense which it should be, the word je is used, which has no definite meaning; for example, ĝoj’i je tio, “to rejoice over it”; rid’i je tio, “to laugh at it”; enu’o je la patr’uj’o, “a longing for one’s fatherland”. In every language different prepositions, sanctioned by usage, are employed in these dubious cases, in the international language, one word, je, suffices for all. Instead of je, the objective without a preposition may be used, when no confusion is to be feared.


The so-called “foreign” words, i.e. words which the greater number of languages have derived from the same source, undergo no change in the international language, beyond conforming to its system of orthography. ― Such is the rule with regard to primary words, derivatives are better formed (from the primary word) according to the rules of the international grammar, e.g. teatr’o, “theatre”, but teatr’a, “theatrical”, (not teatrical’a), etc.


The a of the article, and final o of substantives, may be sometimes dropped euphoniae gratia, e.g. de l’ mond’o for de la mond’o; Ŝiller’ for Ŝiller’o; in such cases an apostrophe should be substituted for the discarded vowel.