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 (Gode & Blair, 1951), 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 (English, French, Italian, Spanish and Portuguese) were dropped. For example, there is neither adjectival agreement (Spanish/Portuguese gatos negros 'black cats'), since this feature is absent in English, nor continuous verb tenses (English I am reading), 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'.