Interlingue is a constructed language. It was called Occidental between 1922 and 1947. Edgar de Wahl, one of the first Esperantists, created it. De Wahl was from the city of Tallinn in Estonia, which was in the Russian Empire but later became its own country. He spoke German, Russian, Estonian and French since he was a child and had natural ability in languages. He is often called de Wahl.
Interlingue looks a lot like languages in the Romance language family: French, Spanish, Italian, and so on. De Wahl made a rule called De Wahl's rule that made changing verbs to nouns easier and more regular. For example, the word exploder (to explode) regularly changes its d to s (making explosion) when following this rule.
Alphabet and pronunciation
Interlingue is written with 26 Latin letters: a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z. The letters of the alphabet are pronounced as a, be, ce, de, e, ef, ge, ha, i, jot, ka, el, em, en, o, pe, qu, er, es, te, u, ve, duplic ve, ix, ypsilon, and zet. Accents are written on the five vowels to indicate irregular stress, with the acute accent (á é í ó ú) preferred, but others (è, ê, etc.) permitted.
The vowels are usually pronounced as follows: a as English father. e open or closed, as English bed and yes. i as English machine. o open or closed as in English door, hot. u as English rule, pull. y is a consonant after a vowel or beginning a word before a vowel, otherwise is pronounced as i.
The consonants are pronounced as in English, with the following exceptions: c when before e and i = [ts]: cive, helice g when before e and i = English s in pleasure: plage, giraffe; but elsewhere c and g are as in can, go ss = [s] as in pass s between vowels = [z]: rose, positiv z = [dz] zz = [ts] ch = [ʃ], English sh: chambre j = [ʒ], English s in pleasure t as [t], except when followed by ia, io, iu, or ie and not preceded by an s. Thus the t in nation is pronounced [ts] but in bastion as [t].
Other doubled consonants are pronounced as a single consonant, unless when separated they would be pronounced differently. Ex. grammatica is pronounced as if written gramatica, but occidental and suggestion are pronounced as if written as oc followed by cidental, and sug followed by gestion.
Article
Like English, Interlingue has a definite article and an indefinite article. The definite article (the) is li, and the indefinite (a, an) is un. Plural of a noun is made by adding -s after a vowel, or -es after most consonants. To avoid pronunciation and stress changes, words ending in -c, -g, and -m only add an -s: un libre, du libres, un angul, tri angules, li tric, li trics, li plug, li plugs, li album, pluri albums, li tram, du trams.
The ending of the definite article can be modified to lo (masculine), la (feminine), lu (neuter), lis (plural), los (masculine plural), e las (feminine plural). Of these, the forms lu and lis are most common: lu in the same sense as Spanish lo and English that which, as in Ne li aprension de un lingue es lu essential, ma su usation (that which is essential is not the learning of a language, but using it), and lis to change to plural words that are difficult to make plural on their own: lis s (the s's).
Personal pronouns
Interlingue has two forms for the personal pronouns: one for the subject form (nominative), and one for the object form (accusative or dative).