Interlingue grammar

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).

		first		second		third (neutral)		third (fem.)		third (masculine)
		ie	en	ie	en	ie	en	ie	en	ie	en
Singular	Subject	yo	I	tu	thee	it	it	ella	she	il	he
	Object	me	me	te	thou	it	it	la	her	le	him
	Possessive	mi	my	tui	thy	su	its	su	her	su	his
Plural	Subject	noi	we	vu	you	ili	they	ellas	they	illos	they
	Object	nos	us	vos	you	les	them	las	them	los	them
	Possessive	nor	our	vor	your	lor	their	lor	their	lor	their

Grammatical endings are used, but less than in Esperanto and Ido in which parts of speech are marked with obligatory endings. Only a few parts of speech (such as verb infinitives) in Interlingue have entirely obligatory endings, while many others either have endings the usage of which is optional and sometimes recommended. Some grammatical endings are:

• ar, er, ir: verb infinitive. far (to do), posser (be able), scrir (to write)
• e: the general noun ending used obligatorily to differentiate nouns from other parts or speech or for reasons of pronunciation. Examples of obligatory -e endings: capitale (capital, noun) vs. capital (capital, adjective), contenete (content) vs, contenet (contained), sud (south, adjective) vs. sude (south as an independent noun, as in the north and the south). A final -e is recommended in words ending with -s to avoid confusion with the plural (curse, sense), -ir, -er- and -ar endings to avoid confusion with the verb infinitive (dangere, desire, papere), and other such areas where its addition aids in differentiation or pronunciation. Optional -e endings: can or cane (dog), Pentecost or Pentecoste (Pentecost).
• i: the general adjectival ending, similar to -e in usage. Examples of obligatory -i endings: pigri (lazy) and acri (sharp) to enable pronunciation, verdi (green, adjective) to distinguish from verde (green, noun). Examples of optional -i endings: etern vs. eterni (eternal), imens vs. imensi (immense).
• a: nouns that end in e formed from an -ar verb are often written with the -a ending if one wishes to emphasize the verbal (active) aspect. A me veni un pensa (a thought occurs to me) vs. Penses e paroles (thoughts and words). The a ending also makes nouns feminine: anglese (English person), angleso (Englishman), anglesa (English woman). This does not apply to nouns that on their own indicate the gender (patre, matre).
• o: indicates the masculine gender in the same way a indicates the feminine.

Correlatives

	QU- (interrogative/relative)	T- (demonstrative)	ALQU- (undefined)	NEQU- (negative)	-CUNC (indeterminate)	Ø (collective)
-I (persons, standard demonstrative)	qui (who)	ti (this/that)	alqui (someone)	nequi (nobody)	quicunc (whoever)	omni (every, all)
-O (things)	quo (what)	to (that: general demonstrative as in "that is true")	alquo (something)	nequo (nothing)	quocunc (whatever)	omno (all)
-EL (both persons and things)	quel (which)	tel (such)	alquel (any)	nequel	quelcunc (whichever)	chascun (each, all)
-AL (quality)	qual (which, what a)	tal (that)	alqual (any kind)	nequal	qualcunc
-AM (way, mode)	quam (as)	tam (so)	alquam (anyhow)	nequam	quamcunc (however)
-ANT (quantity)	quant (how many)	tant (so much)	alquant (somewhat)	nequant	quantcunc
-ANDE (time)	quande (when)	tande (then)	alquande	nequande (never)	quandecunc	sempre (always, ever)
-U (place)	u (where)	ci / ta (here / there)	alcu (somewhere)	necu (nowhere)	ucunc (anywhere)	partú (everywhere)

Notes on the correlatives:

Alcun (some) and necun (no, none) are respectively the adjectives of alquel and nequel.

The -qui series has optional accusative forms ending in -em: quem, alquem, nequem.

The -al series is adverbialized with the -men ending: qualmen (how) talmen (that way).

Correlatives can take the plural ending: queles, quales, tis, omnis, etc.

Ci (here) and ta (there) can be affixed to ti and to to indicate proximity or distance: ti libre (this book), ti-ci libre (this book here), ti-ta libre (that book there), tis (these), tis-ci (these here), tis-ta (those there), to-ci (this here), to-ta (that there).

Many derivatives are formed from the correlatives: qualitá from qual + itá, quantitá from quant + -itá, omnipotent from omni + potent.

Verbs

Verbs in Interlingue have three endings: -ar, -er, and -ir. Conjugation is performed with a combination of endings and auxiliary verbs. The verb esser (to be) is exceptional in being written es in the present tense, though the esse form is seen in the imperative.

Simple Verb Tenses

	Form	Interlingue	English	Notes
Infinitive	ar / er / ir	amar / decider / scrir	to love / to decide / to write
Present	a / e / i	yo ama / decide / scri	I love / decide / write
Past	-t	yo amat / decidet / scrit	I loved / decided / wrote	stress thus falls on the last syllable: yo amat
Future	va + inf.	yo va amar / decider / scrir	I will (shall) love / decide / write	va on its own is not a verb (to go = ear or vader)
Conditional	vell + inf.	yo vell amar / decider / scrir	I would love / decide / write	Also used for hearsay: Un acusation secun quel il vell har esset... - An accusation alleging him to have been... (lit. an accusation according to which he would have been...)
Imperative	a! / e! / i!	ama! / decide! / scri!	love! / decide! / write!	Imperative of esser is esse.

Compound Verb Tenses

	Form	Interlingue	English	Notes
Perfect	ha + t	yo ha amat / decidet / scrit	I have loved / decided / written	ha on its own is not a verb (to have = haver)
Pluperfect	hat + t	yo hat amat / decidet / scrit	I had loved / decided / written
Future Perfect	va har + t	yo va har amat / decidet / scrit	I will (shall) have loved / decided / written
Perfect Conditional	vell har + t	yo vell har amat / decidet / scrit	I would have loved / decided / written
Future in the past	vat + inf.	yo vat amar / decider / scrir	I was going to love / to decide / to write
Precative	ples + inf.	ples amar! / decider! / scrir!	please love! / please / write!
Hortative	lass + inf.	lass nos amar! / decider! / scrir!	let's love! / decide! / write!
Optative	mey + inf.	yo mey amar / decider / scrir	May I love / decide / write	Only the same as English may in the optative mood (as in "May his days be long" or "May the Force be with you", not "I may or may not go").
Present participle	-nt	amant / decident / scrient	loving / deciding / writing	-ir verbs become -ient
Gerund (adverbial participle)	-nte	amante / decidente / scriente	(while) loving / deciding / writing	-ir verbs become -iente

Adverbs

Interlingue has primary adverbs and derived adverbs. Primary adverbs are adverbs without special endings: tre (very), sempre (always), etc.

Derived adverbs are adverbs made by putting -men at the end of an adjective (rapid = quick, rapidmen = quickly). This is similar to -ment in French, -mente in Italian, and other Romance languages. The ending -men was inspired by Provençal and spoken French (which does not pronounce the t in -ment) and chosen over -mente to avoid clashing with the noun ending -ment and other nouns in the language derived from the past tense in -t. The ending may be omitted when the meaning is clear: tu deve far it rapid(men) = you must do it quick(ly).

Dr. F. Haas in 1956 grouped the most common adverbs by type as below.

Genre	Common Adverbs
Manner (How?)	qualmen, quam, talmen, tam, alquam, nequam, solmen, apen, tot, totalmen, totmen, ne totmen, totmen ne
Quantity (How much?)	quant, tant, sat, suficent, nequant, alquant, tre, tro, circa, mult, poc, un poc, quelcvez, multvez, sovente, plu, adplu, sempre, sempre plu, sempre plu mult, sempre plu mult ancor, min, plu o min, maxim, admaxim
Location (Where? To / from where?)	u, ci, ta, alcú, necú, partú, ucunc, supra, infra, circum, éxter, extra, intra, ínter, detra, levul, dextri, proxim, lontan.
Time (When?)	quande, unquande, alquande, nequande, quandecunc, alor, tande, ínterim, nu, strax, subitmen, just, justmen, bentost, tost, tard, temporan, solmen, ne ante, sovente, sempre, ne plu, antey, poy, depoy, desde, in ante, ja, ancor, ne ancor, adplu
Affirmation/ Negation / Doubt (Really?)	yes, no, ne, ne plu, si, ya, fórsan, sin dúbite.