Interlingua grammar


This article is an informal outline of the grammar of Interlingua, an international auxiliary language first publicized by IALA. It follows the usage of the original grammar text, which is accepted today but regarded as conservative.
The grammar of Interlingua is based largely on that of the Romance languages, but simplified, primarily under the influence of English. However, all of the control languages, including German and Russian, were consulted in developing the grammar. Grammatical features absent from any of the primary control languages were dropped. For example, there is neither adjectival agreement , since this feature is absent in English, nor continuous verb tenses, since they are absent in French. Conversely, Interlingua has articles, unlike Russian, as Russian is a secondary control language.
There is no systemic marking for parts of speech. For example, nouns do not have to end in any particular letter. Typically, however, adjectives end in -e or a consonant, adverbs end in -mente or -o, while nouns end in -a, -e, -o or a consonant. Finite verbs virtually always end in -a, -e, or -i, while infinitives add -r: scribe, 'write', 'writes'; scriber, 'to write'.

Articles

The definite article is le and indefinite article is un. They are invariable and are used roughly as in English. The prepositions a and de can optionally be fused with le into al and del respectively.

Nouns

s inflect for number only. Plural nouns take -s after a vowel, -es after a consonant.
Interlingua has no grammatical gender. Animate nouns are sex-neutral, unless they refer specifically to a male or a female. Thus, jornalista 'journalist' and scientista 'scientist' are sex-neutral, while rege 'king' and regina 'queen' are sex-specific. Explicit feminine forms can be created by substituting final -a for a final -o or -e or by adding the suffix -essa.
These colour the regular forms as masculine when they appear in the same context.

Adjectives

Adjectives may precede or follow the noun they modify. As a matter of style, short adjectives tend to precede, long adjectives tend to follow. Numerals always precede the noun.
An adjective never has to agree with the noun it modifies, but adjectives may be pluralized when there is no explicit noun to modify.
Comparative degree is expressed by plus or minus preceding the adjective and superlative degree by le plus or le minus.
The suffix -issime may be used to express the absolute superlative degree.
The adjectives bon 'good', mal 'bad', magne 'great', and parve 'small' have optional irregular forms for the comparative and superlative.

Adverbs

There are two types of adverbs, primary and secondary. Primary adverbs are a closed class of grammatical operators, such as quasi, 'almost'; jam, 'already'; and totevia, 'anyway'. Secondary adverbs are an open class derived from corresponding adjectives by adding the suffix -mente.
A few common adverbs have optional short forms in -o.
Like adjectives, adverbs use plus and minus to express the comparative and le plus and le minus to express the superlative.
The adverbs equivalent to bon, 'good' and mal, 'bad' have optional irregular forms.

Pronouns

Personal pronouns

s inflect for number, case, and gender.
One could also assert the existence of a separate prepositional case, since third-person pronouns use the longer forms ille, illes etc. after a preposition in place of the expected le, les etc.
Many users follow the European custom of using the plural forms vos etc. rather than tu etc. in formal situations.
Illes can be used as a sex-neutral pronoun, like English 'they'. Illas may be used for entirely female groups.

Impersonal pronouns

Il is an impersonal nominative pronoun used in constructions like il pluve, 'it's raining'. It can also serve as a placeholder when the true subject is a clause occurring later in the sentence. It may be omitted where the sense is clear.
On is a nominative pronoun used when the identity of the subject is vague. The English translation is often 'one', 'you', or 'they'. It is sometimes equivalent to an English passive voice construction. The oblique form is uno.

Demonstratives

The main demonstratives are the adjective iste, 'this' and the corresponding pronouns iste, ista, and isto, which may be pluralized. They are used more widely than English 'this/these', often encroaching on the territory of English 'that/those'. Where the subject of a sentence has two plausible antecedents, iste refers to the second one.
The demonstrative of remoteness is ille 'that'. The corresponding pronouns ille, illa, illo and their plurals are identical with the third-person personal pronouns, though they are normally accentuated in speech.

Relative and interrogative pronouns

The relative pronouns for animates are qui and que.
For inanimates, que covers both the nominative and oblique cases.
Cuje 'whose' is the genitive case for both animates and inanimates.
All the above may be replaced by the relative adjective forms le qual and le quales.
The relative pronouns also serve as interrogative pronouns.

Verbs

The verb system is a simplified version of the systems found in English and the Romance languages. There is no imperfective aspect, as in Romance, no perfect as in English, and no continuous aspect, as in English and some Romance languages. Except for esser 'to be', there are no personal inflections, and the indicative also covers the subjunctive and imperative moods. Three common verbs usually take short forms in the present tense, and a few optional irregular verbs are available.
For convenience' sake, this section often uses the term tense to also cover mood and aspect, though this is not strict grammatical terminology.
The table at the right shows the main verb forms, with examples for -ar, -er and -ir verbs.
The simple past, future, and conditional tenses correspond to semantically identical compound tenses. These in turn furnish patterns for building more-complex tenses such as the future perfect.

Infinitives

verbs always end in -ar, -er, or -ir. They cover the functions of both the infinitive and the gerund in English and can be pluralized where it makes sense.
Infinitives are also used in some compound tenses.

Simple tenses

There are four simple tenses: the present, past, future, and conditional.
The present participle is effectively the present tense form plus -nte. Verbs in -ir take -iente rather than *-inte. It functions as an adjective or as the verb in a participial phrase.
The past participle can be constructed by adding -te to the present tense form, except that -er verbs go to -ite rather than *-ete. It is used as an adjective and to form various compound tenses.

Compound tenses

Three compound tenses – the compound past, future, and conditional – are semantically identical with the corresponding simple tenses.
The fourth basic compound tense is the passive, formed from es plus the past participle.
A wide variety of complex tenses can be created following the above patterns, by replacing ha, va, and es with other forms of haber, vader, and esser. Examples:
There are no distinct forms for the imperative and subjunctive moods, except in the case of esser 'to be'. Present-tense forms normally serve both functions. For clarity's sake, a nominative pronoun may be added after the verb.
The infinitive can serve as another, stylistically more impersonal, imperative form.
A less urgent version of imperative, the cohortative, employs a present-tense verb within a "that" clause and may be used with the first and third person as well as the second. The alternative vamos 'let's' is available for the second-person plural, but deprecated by some authorities.
Sia is the imperative and subjunctive form of esser 'to be'. The regular form esse may also be used.

Irregular verbs

The only irregular verb forms employed by most users are es, ha, and va – the shortened present-tense forms of esser 'to be', haber 'to have' and vader 'to go' – plus sia, the imperative/subjunctive of esser.
Other irregular forms are available, but official Interlingua publications have always favoured the regular forms. These optional irregular forms are known as collaterals.
A significant minority of users employ certain collateral forms of esser 'to be': son, era, sera, and serea, instead of es, esseva, essera, and esserea.
The forms io so 'I am' and nos somos 'we are' also exist but are rarely used.

Double-stem verbs

The Neolatin vocabulary that underlies Interlingua includes a group of verbs whose stems mutate when attached to certain suffixes. For example, agente, agentia, actrice, activista, reagente, reaction are all derivatives of ager 'to act', but some use the primary stem ag-, while others use the secondary stem act-. There are hundreds of such verbs, especially in international scientific vocabulary.
This raises a logical issue. Adding -e to one of these secondary stems produces an adjective that is structurally and semantically equivalent to the past participle of the same verb. Experte, for example, is related to experir 'to experience', which has the past participle experite. Yet, semantically, there is little difference between un experte carpentero 'an expert carpenter' and un experite carpentero 'an experienced carpenter'. Effectively, experte = experite. Furthermore, one can form a word like le experito 'the experienced one' as a quasi-synonym of le experto 'the expert'.
This process can be reversed. That is, can one substitute experte for experite in compound tenses.
The original Interlingua grammar permitted this usage, and illustrated it in one experimental text. A minority of Interlinguists employ the irregular roots, at least occasionally, more often with recognizable forms like scripte than opaque ones like fisse. The practice is controversial. Deprecators suggest that they complicate the active use of Interlingua and may confuse beginners. Proponents argue that by using the irregular participles, students of Interlingua become more aware of the connections between words like agente and actor, consequentia and consecutive, and so on. A compromise position holds that the irregular forms may be useful in some educational contexts, but not in general communication.
A similar issue concerns the present participles of caper 'to grasp, seize', facer 'to do, make', saper 'to know', and all verbs ending in -ciper, -ficer, and -jicer. The regular forms are facente, sapente, etc., but the "preferred forms", according to the original grammar, are faciente, sapiente, etc.
Today, most users employ the regular forms in spontaneous usage. Forms like sufficiente'' are often used as adjectives, under the influence of similar forms in the source languages.

Syntax

The normal word order in Interlingua is subject–verb–object, though this may be relaxed where the sense is clear.
Pronouns, however, tend to follow the Romance pattern subject–object–verb, except for infinitives and imperatives, where the object follows the verb.
When two pronouns, one a direct and one an indirect object, occur with the same verb, the indirect object comes first.
The position of adverbs and adverbial phrases is similar to English.

Questions

can be created in several ways, familiar to French speakers.