Infinitive (imperfective): забыва́ть — "to forget (as a process / habitually)" Infinitive (perfective): забы́ть — "to forget (one completed act); to leave behind" Type: a regular aspect pair built with the -ва- imperfectivising suffix (забы́ть → забыва́ть)
Forgetting is, by its nature, usually a single completed event — you forget something once — so this verb leans heavily on its perfective, забы́ть. The imperfective забыва́ть is built from it with the productive -ва- suffix (see pair-formation by suffix), and it covers habitual or repeated forgetting. The verb also carries two distinct case patterns — forget a thing (accusative) and forget about something (о + prepositional) — and it gives Russian one of its most-used warnings, Не забу́дь! "Don't forget!". This page lays out the forms, the stress, and exactly when each case applies.
Present tense (забыва́ть, imperfective) — first conjugation
A perfective has no present, so only забыва́ть has one. It is a textbook first-conjugation -ай verb (like чита́ть, де́лать): the stem keeps -ва- and the stress sits on -ва́-.
| Person | забыва́ть — PRESENT |
|---|---|
| я | забыва́ю |
| ты | забыва́ешь |
| он / она́ / оно́ | забыва́ет |
| мы | забыва́ем |
| вы | забыва́ете |
| они́ | забыва́ют |
These are the easy -ю/-ешь/-ет endings; the stress never moves off -ва́-. The imperfective present is for habitual or repeated forgetting: "I keep forgetting," "I always forget."
Я ве́чно забыва́ю, где оставля́ю ключи́.
I'm forever forgetting where I leave my keys. — забыва́ю: a habit, imperfective present.
С во́зрастом мы забыва́ем имена́, но по́мним ли́ца.
With age we forget names but remember faces. — забыва́ем: a general, repeated truth, imperfective.
Past tense
Both members build a regular, gender-marked past. Stress stays put — on -ва́- for the imperfective and on -бы́- for the perfective — with no shifts.
| Gender / number | забыва́ть (impf) | забы́ть (pf) |
|---|---|---|
| masculine | забыва́л | забы́л |
| feminine | забыва́ла | забы́ла |
| neuter | забыва́ло | забы́ло |
| plural | забыва́ли | забы́ли |
The aspect contrast is unusually clear with this verb. забы́л is the default for a single act of forgetting ("I forgot [and it caused a problem]"). забыва́л is for repetition or a process ("I kept forgetting / I was forgetting") — and there is a special pattern: я забыва́л can mean "I used to forget but no longer," because the imperfective leaves the result open.
Извини́, я совсе́м забы́л о встре́че.
Sorry, I completely forgot about the meeting. — забы́л: one completed act, perfective.
Она́ забы́ла зонт в по́езде.
She left her umbrella on the train. — забы́ть 'leave behind' + accusative (зонт); perfective.
Ра́ньше я постоя́нно забыва́л пароли́.
I used to constantly forget passwords. — забыва́л: repeated, habitual forgetting, imperfective.
Future tense
The two members form the future the two standard ways.
- забыва́ть (imperfective) → compound future: бу́ду забыва́ть "I'll keep forgetting" (rare — you rarely promise to forget repeatedly).
- забы́ть (perfective) → simple future: the забу́д- forms, each one completed future act.
| Person | забыва́ть → бу́ду забыва́ть | забы́ть → simple future |
|---|---|---|
| я | бу́ду забыва́ть | забу́ду |
| ты | бу́дешь забыва́ть | забу́дешь |
| он / она́ / оно́ | бу́дет забыва́ть | забу́дет |
| мы | бу́дем забыва́ть | забу́дем |
| вы | бу́дете забыва́ть | забу́дете |
| они́ | бу́дут забыва́ть | забу́дут |
The forms забу́ду, забу́дешь… забу́дут look present but are the future (perfective забы́ть has no present). The stem switches from infinitive забы́ть to забу́д- — learn it as a block. The most frequent real-life use is the negated future as a promise: Я не забу́ду "I won't forget."
Не волну́йся, я не забу́ду тебя́ встре́тить.
Don't worry, I won't forget to come and meet you. — забу́ду: perfective simple future; negated promise.
Я э́того никогда́ не забу́ду.
I'll never forget this. — забу́ду + genitive of negation (э́того); a fixed emotional turn of phrase.
Imperative
The imperative is where this verb earns its keep: the perfective negative imperative Не забу́дь! "Don't forget!" is one of the most-heard warnings in Russian.
| Addressee | забыва́ть (impf) | забы́ть (pf) |
|---|---|---|
| ты (informal) | забыва́й | забу́дь |
| вы (formal / plural) | забыва́йте | забу́дьте |
Russian normally bars perfective verbs from the negative imperative — не + perfective usually warns of an accidental, unwanted outcome rather than forbidding an action. Не забу́дь! is exactly that: "(make sure you) don't forget!", a caution against an accidental lapse. Contrast the positive imperatives: perfective Забу́дь! "Forget it! / Drop it!" (one decisive act — telling someone to let something go), and imperfective Не забыва́й "don't keep forgetting / stay in touch."
Не забу́дь купи́ть хлеб!
Don't forget to buy bread! — Не забу́дь: the everyday perfective warning against an accidental lapse.
Забу́дь о нём, он того́ не сто́ит.
Forget about him, he's not worth it. — positive perfective Забу́дь: 'let it go', one decisive act.
Не забыва́й нас, звони́ ча́ще!
Don't forget us, call more often! — imperfective Не забыва́й: 'stay in touch', an ongoing relationship.
Participles and verbal adverbs
| Form | забыва́ть (impf) | забы́ть (pf) |
|---|---|---|
| present active participle | забыва́ющий | — |
| past active participle | забыва́вший | забы́вший |
| past passive participle | — | забы́тый "forgotten" |
| verbal adverb | забыва́я "while forgetting" | забы́в "having forgotten" |
The high-value form is the perfective passive participle забы́тый "forgotten" — забы́тый го́род "a forgotten city," забы́тые слова́ "forgotten words." The verbal adverb забы́в "having forgotten" is common in writing: Забы́в зонт до́ма, она́ промо́кла "Having left her umbrella at home, she got soaked."
Забы́в па́спорт, он не смог сесть на самолёт.
Having forgotten his passport, he couldn't board the plane. — verbal adverb забы́в.
Key uses & collocations
1. забы́ть + accusative — forget / leave a thing
To forget a concrete thing, or to leave it behind somewhere, use the accusative direct object: забы́ть зонт, ключи́, телефо́н, и́мя. See accusative direct object. For "leave behind in a place," add a location: забы́ть зонт в по́езде.
Я забы́л телефо́н на рабо́те.
I left my phone at work. — accusative телефо́н + location в/на; the 'leave behind' sense.
2. забы́ть о + prepositional — forget about something
To forget about an abstract matter — a fact, a plan, an appointment — use о + prepositional, the same "about" construction you meet in о + prepositional: забы́ть о встре́че, о про́шлом, об экза́мене. There is a nuance: забы́ть встре́чу (accusative) means you blanked the meeting itself; забы́ть о встре́че (о + prep.) means it slipped your mind that it was happening. Both are correct; о + prepositional is the more common for appointments and plans.
Дава́й забу́дем о ссо́ре и помири́мся.
Let's forget about the quarrel and make up. — забы́ть о + prepositional (ссо́ре).
3. забы́ть + infinitive — forget to do
To forget to do something, follow забы́ть with an infinitive (usually perfective): забы́ть закры́ть дверь, забы́ть позвони́ть.
Он забы́л вы́ключить плиту́.
He forgot to turn off the stove. — забы́ть + perfective infinitive (вы́ключить).
Common Mistakes
❌ За́втра я бу́ду забы́ть твой день рожде́ния.
Aspect error — the бу́ду future needs an imperfective infinitive. The perfective забы́ть makes its own future: забу́ду (no бу́ду).
✅ Я не забу́ду твой день рожде́ния.
I won't forget your birthday.
❌ Я забу́ю / забу́дю / забы́ю…
Spelling/stem error — the perfective future is забу́ду / забу́дешь / забу́дут (stem забу́д-), not 'забу́ю'.
✅ Я обяза́тельно забу́ду, е́сли не запишу́.
I'll definitely forget if I don't write it down.
❌ Я забы́л об мой зонт.
Government mix — for a concrete thing use the accusative (забы́л зонт); о + prepositional is for forgetting ABOUT a matter (забы́л о встре́че).
✅ Я забы́л зонт. / Я забы́л о встре́че.
I forgot my umbrella. / I forgot about the meeting.
❌ Не забу́дешь купи́ть хлеб!
Wrong form for the warning — the negative imperative is Не забу́дь(те)!, not the future indicative.
✅ Не забу́дь купи́ть хлеб!
Don't forget to buy bread!
Key Takeaways
- Aspect pair via -ва-: perfective забы́ть → imperfective забыва́ть. Forgetting is usually a one-off, so забы́л is the default; забыва́л / забыва́ю is for repeated/habitual forgetting.
- Present (забыва́ть only): забыва́ю / забыва́ешь … забыва́ют — first conjugation, stress on -ва́-.
- Future: perfective stem switches to забу́д- (забу́ду / забу́дешь / забу́дут) — looks present, is future; everyday "I won't forget" = я не забу́ду.
- Imperative: Не забу́дь! "don't forget!" (perfective warning) vs Забу́дь! "forget it!" vs Не забыва́й "stay in touch."
- Government: забы́ть что (accusative — a thing / leave behind) vs забы́ть о чём (о + prepositional — about a matter); забы́ть + infinitive "forget to do."
- Useful participle: забы́тый "forgotten."
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