The choice between one н and two is one of the genuinely hard corners of Russian orthography — even educated native speakers hesitate over it, and it is a fixture of school spelling exams. The good news is that the chaos resolves into a few clear questions, and once you know which question to ask for which kind of word, most cases fall out cleanly. The trap is trying to spell by ear: н and нн are pronounced identically. Everything here is morphology made visible — you must know what the word is (a participle? a short form? a denominal adjective?) before you can spell it.
Participles: full -нн-, short -н-
A past passive participle ("written," "read," "built") is formed from a verb. The first and most reliable split is between its full (long) form and its short form.
Full participles from perfective verbs → -нн-
A full past passive participle built from a perfective verb (a completed action, usually with a prefix) takes -нн-.
Прочи́танная кни́га лежа́ла на столе́.
The read book lay on the table. — прочи́танный: full participle from perfective прочита́ть → нн.
Э́то письмо́, напи́санное от руки́.
This is a letter written by hand. — напи́санное: full participle from перфектив написа́ть → нн.
A full participle also takes -нн- if it has a dependent word (an object or adverb) even from a less obviously perfective base, or if it carries a prefix — both are signs it is functioning as a true participle.
Жа́ренная на ма́сле карто́шка осо́бенно вку́сная.
Potatoes fried in oil are especially tasty. — жа́ренная here has a dependent phrase 'на масле', so it's a participle → нн.
Short participles → one -н-
When you turn that participle into its short (predicative) form — the form that works like an English passive "was written," "is built" — it drops to one н. This is exceptionless and is your single most useful anchor.
Письмо́ напи́сано аккура́тно.
The letter is written neatly. — short participle напи́сан → one н.
Все зада́ния уже́ прочи́таны.
All the assignments have already been read. — short participle прочи́таны → one н.
Дом постро́ен в про́шлом году́.
The house was built last year. — short participle постро́ен → one н.
Denominal adjectives: it's all about the suffix
Adjectives built from nouns (not from verbs) are governed by their suffix. This is a pure list, but a short and stable one.
-онн- / -енн- → -нн-
| Adjective | From noun | Suffix |
|---|---|---|
| революцио́нный (revolutionary) | револю́ция | -онн- |
| традицио́нный (traditional) | тради́ция | -онн- |
| иску́сственный (artificial) | иску́сство | -енн- |
| ка́менный (stone, of stone) | ка́мень | -енн- |
Also in this -нн- camp are adjectives where the noun stem already ends in н and the suffix -н- is added, doubling it: дли́нный (длин-а + -н-), стари́нный (старин-а + -н-).
Они́ жи́ли в ста́ром ка́менном до́ме.
They lived in an old stone house. — ка́менный, -енн- → нн.
У неё дли́нные тёмные во́лосы.
She has long dark hair. — дли́нный: длин- + -н- = нн.
-ан- / -ян- / -ин- → one -н-
Adjectives meaning "made of" or "relating to" an animal usually take a single н via the suffixes -ан-, -ян-, -ин-.
| Adjective | From noun | Suffix |
|---|---|---|
| ко́жаный (leather, of leather) | ко́жа | -ан- |
| сере́бряный (silver, of silver) | серебро́ | -ян- |
| ку́риный (chicken's, of a hen) | ку́рица | -ин- |
| гуси́ный (goose's) | гусь | -ин- |
Он наде́л ста́рую ко́жаную ку́ртку.
He put on an old leather jacket. — ко́жаный, -ан- → one н.
Она́ подари́ла мне сере́бряное кольцо́.
She gave me a silver ring. — сере́бряный, -ян- → one н.
На за́втрак был кури́ный бульо́н.
There was chicken broth for breakfast. — кури́ный, -ин- → one н.
The three exceptions you must memorise
Three -ян-/-янн- adjectives break the "one н" pattern and take -нн-. There is no logic — memorise them as a set, ideally with the classic mnemonic image of a glass-tin-wooden trio.
Окно́ закры́то стекля́нной две́рью.
The window is closed off by a glass door. — стекля́нный: exception, нн.
На по́лке стои́т оловя́нный солда́тик.
A tin soldier stands on the shelf. — оловя́нный: exception, нн.
Они́ постро́или деревя́нный дом.
They built a wooden house. — деревя́нный: exception, нн.
Verbal adjective vs participle: жа́реный / зажа́ренный
The subtlest split is between a true participle and an adjective that merely looks verb-derived. A word formed from an imperfective verb with no prefix and no dependent words is treated as an ordinary adjective and takes one н. Add a prefix (making it perfective) or a dependent word, and it becomes a participle → нн.
| One н (verbal adjective) | нн (participle) |
|---|---|
| жа́реный (fried) — from жа́рить, no prefix | зажа́ренный (fried up) — prefix за- → perfective |
| варёный (boiled) | сва́ренный (cooked, boiled) — prefix с- |
| кра́шеный (painted, dyed) | покра́шенный (painted) — prefix по- |
На у́жин — жа́реная ры́ба.
Fried fish for dinner. — жа́реный: no prefix, no dependent word → adjective, one н.
Зажа́ренная до ко́рочки ры́ба пахла́ потряса́юще.
Fish fried to a crisp smelled amazing. — зажа́ренный: prefix за- → participle → нн.
Я люблю́ жа́ренную на гри́ле ку́рицу.
I love grilled chicken. — here 'на гри́ле' is a dependent phrase, so it becomes a participle → нн (жа́ренную).
The distinguishing insight
The whole н/нн system is impossible to spell by sound and easy to spell by category. Before writing the word, classify it: Is it a short form? → one н, always. Is it a denominal adjective? → check the suffix (-онн-/-енн- and "stem-н + -н-" give нн; -ан-/-ян-/-ин- give one н, minus the three glass-tin-wooden exceptions). Is it built from a verb as a full form? → нн if it's perfective, prefixed, or carries a dependent word; one н if it's a bare imperfective verbal adjective. Ask the questions in that order and the spelling stops being a coin-flip.
Common Mistakes
❌ Письмо́ напи́санно аккура́тно.
Incorrect — this is a short participle (predicate), so it takes one н.
✅ Письмо́ напи́сано аккура́тно.
The letter is written neatly. — short form напи́сано, one н.
❌ Он наде́л ко́жанную ку́ртку.
Incorrect — ко́жаный has the suffix -ан-, which takes one н.
✅ Он наде́л ко́жаную ку́ртку.
He put on a leather jacket. — ко́жаный, one н.
❌ Они́ постро́или деревя́ный дом.
Incorrect — деревя́нный is one of the three memorised exceptions and takes нн.
✅ Они́ постро́или деревя́нный дом.
They built a wooden house. — деревя́нный with нн.
❌ Прочи́таная кни́га лежа́ла на столе́.
Incorrect — a full participle from perfective прочита́ть takes нн.
✅ Прочи́танная кни́га лежа́ла на столе́.
The read book lay on the table. — прочи́танная with нн.
❌ На у́жин — жа́ренная ры́ба (meaning plain 'fried fish').
Incorrect when there's no prefix and no dependent word — bare жа́реный is a verbal adjective with one н.
✅ На у́жин — жа́реная ры́ба.
Fried fish for dinner. — жа́реный, one н (adjective).
Key Takeaways
- Don't spell by ear — н and нн sound identical. Classify the word first.
- Full participles from perfective/prefixed verbs, or with a dependent word → -нн- (напи́санный, прочи́танный); their short forms → one -н- (напи́сан, прочи́тан, постро́ен).
- Denominal adjectives: suffixes -онн-/-енн- → нн (революцио́нный, ка́менный, дли́нный); -ан-/-ян-/-ин- → one н (ко́жаный, сере́бряный, ку́риный).
- Memorise the three -нн- exceptions: стекля́нный, оловя́нный, деревя́нный.
- A bare imperfective verbal adjective takes one н (жа́реный, варёный); add a prefix or a dependent word and it becomes a participle → нн (зажа́ренный).
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