Hiatus and Double Vowels (alee, fiică, copiii)

When two vowels sit next to each other in Romanian, one of two things is happening, and they sound completely different. Either the vowels glide together into one syllable — a diphthong, like ea in seară — or they belong to separate syllables with a tiny re-articulation between them — a hiatus, like the two e's in alee (a-le-e). English speakers, trained by a spelling system where doubled and adjacent vowels almost always collapse (see, moon, boat are all one syllable), instinctively merge every vowel cluster, and so they say fi-că for fiică and co-pii for copiii. But Romanian counts those extra vowels as full syllables — and since syllable count determines where the stress lands and how the rhythm goes, getting hiatus wrong throws off the whole word. This page is about telling hiatus from diphthong, and about the famously vowel-heavy words like copiii that frighten learners until you slow them down.

Diphthong vs. hiatus: the core distinction

A diphthong is one syllable: the tongue glides smoothly from one vowel into another with no break (ea, oa, ia — see the diphthongs page). A hiatus is two syllables: each vowel is fully formed, with a small fresh start between them, like the two vowels in English "co-operate" or "re-enter." The difference is audible — floa-re (diphthong, two syllables) versus al-co-ol (hiatus, three syllables).

There is no foolproof spelling cue, which is the honest difficulty here — oa is almost always a diphthong but o-o (two separate o letters) is always hiatus; ea is usually a diphthong but in a few learned words (real, teatru) it is hiatus (re-al, te-a-tru). You will absorb most of these by exposure, but the structural ones below are predictable.

Doubled vowels are always hiatus

When the same vowel letter is written twice in a row, it is never a single long sound and never a diphthong — it is two syllables, hiatus. This is the cleanest, most reliable case. Alcool has o-o across two syllables; fiică has i-i; the verb a crea (to create) gives cre-ez, cre-at with the e-e of creează (cre-ea-ză) showing both hiatus and a following diphthong. The two identical vowels each get their own beat, with a slight pulse between them.

The -ii endings: where the i's pile up

Romanian's most intimidating-looking words come from stacking grammatical -i endings on a stem that already ends in i. Each -i has a job, and once you see the morphology the pronunciation falls out. There are three sources of i:

1. a stem ending in i (as in copil → plural stem copi-),
2. the plural marker -i,
3. the definite article -i (the masculine plural "the").

Stack them and you get the famous copiii (the children), which is co-pi-ii — the stem copi-, then a doubled i spelling the plural-plus-article, pronounced as a single long /iː/ or a re-articulated i-i. Compare the layers:

So the difference between copii (children) and copiii (the children) is the third i: the article. In speech copii ends in a long /ij/-like i, and copiii adds the article's i on top, giving a noticeably longer, doubled final vowel — co-pi-ii. The same pattern produces fii (sons) → fiii (the sons), and vii (alive, pl.) versus the verb vii (you come).

ființă, ființe: hiatus inside common words

Hiatus is not just in showy words like copiii; it hides in ordinary vocabulary. Ființă (being, creature) is fi-in-ță — the i-i is hiatus, two syllables, not a long single i. A ști (to know) gives știință (ști-in-ță, science) with the same i-i hiatus. Trebuință (need, tre-bu-in-ță) and folosință (use, fo-lo-sin-ță) and similar -ință nouns keep their vowels apart. The pattern is that an i belonging to the stem and an i belonging to a suffix do not merge — each holds its syllable.

Why this matters: stress and rhythm depend on the count

Syllable count is not pedantry — it determines stress placement and the rhythm of the word, and a wrong count derails both. If you collapse fiică (fi-i-că, 3) into fi-că (2), you not only lose a syllable, you move where the stress sits and the word stops sounding like a word. If you say co-pii for copiii, you have said "children" when you meant "the children" — a grammatical error produced by a pronunciation shortcut. And in poetry, song, and any counted-syllable context, hiatus versus diphthong changes the meter entirely (re-al is two syllables, real the English way is one). Slowing down to give each hiatus vowel its own beat is what fixes it.

Source-language comparison

English aggressively collapses adjacent and doubled vowels: see, too, moon, boat, beauty are all single syllables, and even genuine hiatus words like cooperate and reentry are often rushed. So the English ear and mouth default to "merge," which is precisely the wrong instinct for Romanian hiatus. The other Romance languages share Romanian's habit of keeping many vowels apart (Spanish le-er, Italian po-e-ta), so if you know one of those, the concept of hiatus is familiar — but Romanian's specific -i stacking (the copiii phenomenon) is its own beast, driven by gluing the definite article onto plurals, something Spanish and Italian don't do.

Common Mistakes

Collapsing the doubled i of fiică into one syllable:

Saying copii (two i's) when you mean copiii (the children, three i's):

Merging the o-o of alcool into one long /o/:

Treating alee as one or two syllables instead of three:

Reading ființă with a single long i:

Key Takeaways

• Adjacent vowels are either a diphthong (one syllable, gliding) or hiatus (two syllables, re-articulated): floa-re vs al-co-ol.
• Doubled vowel letters are always hiatus: alcool (al-co-ol), fiică (fi-i-că), alee (a-le-e), cooperare (co-o-pe-ra-re).
• The triple-i copiii is morphology: stem copi-
  • plural -i
    • article -i = co-pi-ii ("the children"), one i more than copii ("children").
• Hiatus hides in common words too: ființă (fi-in-ță), știință (ști-in-ță).
• Syllable count drives stress and rhythm, so collapsing hiatus produces wrong stress and sometimes wrong grammar.
• English's merge-everything instinct is the error to unlearn; give each hiatus vowel its own beat.