An Esperanto compound noun behaves grammatically as one noun. In lingvokurso “language course,” the final element kurs- is the head and the whole compound takes noun -o, plural -j, and accusative -n. An outside adjective describes that complete head expression: intensa lingvokurso, intensaj lingvokursoj.
The harder issue is semantic scope. An adjective placed outside a compound normally describes the whole compound, especially its final head; it does not automatically reach inside to modify the first element. When the intended adjective belongs to an embedded noun phrase, Esperanto usually states that structure explicitly.
Agreement treats the compound as one noun
The internal elements do not carry separate number or case endings. A compound may contain a linking vowel: the first -o- in lingvokurso helps connect lingv- to kurs-, but it does not make lingvo an independently inflected noun phrase. Only the final form of the compound receives plural -j or accusative -n, and the outer adjective agrees with that whole form.
| Role | Phrase |
|---|---|
| singular subject | intensa lingvokurso |
| plural subject | intensaj lingvokursoj |
| singular object | intensan lingvokurson |
| plural object | intensajn lingvokursojn |
Intensa lingvokurso komenciĝos lunde.
An intensive language course will begin on Monday.
Intensaj lingvokursoj komenciĝos lunde.
Intensive language courses will begin on Monday.
Mi elektis du intensajn lingvokursojn por la somero.
I chose two intensive language courses for the summer.
The minimal contrast intensa lingvokurso → intensaj lingvokursoj marks singular versus plural on both adjective and compound noun. The object phrase adds -n to both: intensajn lingvokursojn. The numeral du remains unchanged.
The final element is the compound head
In the ordinary Esperanto compound, the final root gives the broad category and the preceding material narrows it:
- lingvokurso is a kind of kurso
- urbobuso is a kind of buso
- vinbotelo is a kind of botelo
- infanlibro is a kind of libro
This head structure explains both meaning and agreement.
La nova urbobuso havas pli larĝajn pordojn.
The new city bus has wider doors.
Nova describes the bus as a whole: a newly introduced, manufactured, or acquired city bus. It does not mean that the city is new. If the city itself is new, say so in an explicit phrase, such as buso de la nova urbo.
Ŝi rekomendis interesan infanlibron pri kosmovojaĝo.
She recommended an interesting children’s book about space travel.
Here interesan evaluates the book. The first compound element infan- classifies its intended audience or association. Esperanto compounds compress a relation, but the external adjective retains scope over the whole compound.
The compound itself can form a wider word family: lingvokurso → lingvokursa programo. The ending -a applies to the full stable compound, yielding “related to a language course.” Productive morphology operates on compounds just as it does on simple roots.
External adjective versus internal meaning
Compare a red container and red contents:
Sur la breto staras ruĝa vinbotelo.
A red wine bottle is standing on the shelf—the bottle is red.
Sur la tablo staras botelo da ruĝa vino.
A bottle of red wine is standing on the table—the wine is red.
In ruĝa vinbotelo, the adjective is outside the compound and naturally describes vinbotelo, whose head is “bottle.” To make ruĝa modify vino, unpack the relation as botelo da ruĝa vino. Word order alone cannot make an outer adjective secretly agree with an internal root that has no grammatical ending.
Ni mendis grandan kafotason, ne tason da forta kafo.
We ordered a large coffee cup, not a cup of strong coffee.
Grandan describes the cup. Forta belongs to the embedded noun phrase forta kafo. This distinction is semantic as well as formal.
Compound or relational adjective?
Esperanto often offers two compact structures: a compound noun or an -a relational adjective plus noun.
- lingvokurso / lingva kurso
- urbobuso / urba buso
- universitatbiblioteko / universitata biblioteko
The alternatives can overlap, but they do not guarantee identical conventional meanings. A compound tends to name a recognized subtype; an adjective phrase can state a looser relation. Established usage decides which is most natural.
La universitata biblioteko aĉetis novan vortaron.
The university library bought a new dictionary.
La renovigita universitata biblioteko estas hela kaj silenta.
The renovated university library is bright and quiet.
The relational adjective universitata stays close in meaning to the head biblioteko, while renovigita describes the entire institutional library. Both still agree with the same noun.
English readily places an unmarked noun before another noun. Esperanto does not normally write two independent -o words in that pattern. Choose a true compound (lingvokurso), an -a modifier (lingva kurso), or an explicit relation (kurso pri lingvo).
Nested noun phrases: agreement by membership
Longer noun phrases may contain a prepositional phrase with its own noun and adjective. Do not make the embedded adjective copy the outer phrase’s case merely because it is nearby.
Novaj kursoj pri aziaj lingvoj aperis en la katalogo.
New courses on Asian languages appeared in the catalog.
Mi elektis novajn kursojn pri aziaj lingvoj.
I chose new courses on Asian languages.
The outer phrase changes from subject novaj kursoj to object novajn kursojn. The inner phrase pri aziaj lingvoj remains non-accusative because pri governs it. Aziaj agrees with lingvoj, not with nearby kursojn.
Ĉu vi legis la novan raporton de la internacia esplorgrupo? — Ne, mi legis nur la mallongan resumon.
Did you read the new report by the international research group? — No, I read only the short summary.
In the question, novan belongs to object raporton. Internacia belongs to esplorgrupo inside the de phrase. Phrase membership, not proximity, determines agreement.
Predicative adjectives and compounds
A compound noun can be described through esti. The predicative adjective agrees in number with the subject but never takes accusative -n merely because it follows the verb.
La lingvokurso estas intensa, sed la vesperaj lecionoj estas mallongaj.
The language course is intensive, but the evening lessons are short.
Intensa is singular with lingvokurso; mallongaj is plural with lecionoj. See adjectives after esti for the full predicate pattern.
Ellipsis and substantivization
When context makes a compound head recoverable, an adjective can stand for the omitted noun phrase and retain its required endings.
El la du retkursoj mi elektis la pli mallongan, ne la pli multekostan.
Of the two online courses, I chose the shorter one, not the more expensive one.
Both mallongan and multekostan stand for an understood singular object retkurson. This is contextual ellipsis, not a change of the adjective into a permanently lexicalized noun. The listener must be able to recover the omitted head.
Common Mistakes
1. Leaving the adjective singular before a plural compound. Agreement targets the whole compound noun.
❌ Nova lingvokursoj komenciĝos lunde.
Incorrect — plural lingvokursoj requires novaj.
✅ Novaj lingvokursoj komenciĝos lunde.
New language courses will begin on Monday.
2. Omitting accusative agreement on an object compound. Mark both adjective and noun.
❌ Mi elektis intensaj retkursojn.
Incorrect — the plural object adjective needs -jn.
✅ Mi elektis intensajn retkursojn.
I chose intensive online courses.
3. Matching an embedded adjective to the nearest outer object. Respect the prepositional boundary.
❌ Ni legis gravajn artikolojn pri novajn teknologiojn.
Incorrect — the phrase after pri does not receive the outer accusative.
✅ Ni legis gravajn artikolojn pri novaj teknologioj.
We read important articles about new technologies.
4. Expecting an outside adjective to modify an internal compound root. Unpack the phrase when the inner element needs description.
❌ Ŝi mendis ruĝan vinbotelon.
Wrong for the intended meaning ‘a bottle of red wine’ — ruĝan describes the bottle.
✅ Ŝi mendis botelon da ruĝa vino.
She ordered a bottle of red wine.
5. Copying an English noun+noun sequence. Use -a, a compound, or a preposition.
❌ La lingvo kurso daŭras tri semajnojn.
Incorrect — two independent nouns cannot form an English-style modifier sequence.
✅ La lingvokurso daŭras tri semajnojn.
The language course lasts three weeks.
Key Takeaways
- A compound noun behaves as one head and takes one final set of -o/-j/-n endings.
- Direct adjectives agree with the whole compound in number and accusative case.
- An outside adjective normally describes the complete compound, not an internal first root.
- Explicit prepositional phrases reveal inner scope and create their own agreement domains.
- Esperanto replaces English noun stacks with compounds, -a modifiers, or marked relations.
Related Topics
- Adjective ScopeB1 — How word order, agreement, phrase boundaries, degree words, and rewriting show exactly what an Esperanto adjective describes.
- Multiple AdjectivesB1 — Combine Esperanto adjectives clearly, coordinate them with or without kaj, and use agreement and order to show scope.
- Adjective Agreement in the AccusativeA1 — Learn when Esperanto adjectives copy the accusative -n, how -ajn is built, and why predicative adjectives normally remain without -n.
- Compound Head OrderA2 — Interpret and build ordinary Esperanto compounds with the general head on the right and its modifier before it.
- Transparent Noun CompoundsB1 — Build transparent Esperanto nouns by placing a specifying element before the semantic head, while keeping implicit relations and lexical convention clear.