"To forget" is the aspect pair zapomenout / zapomínat, and it earns a place among the irregular verbs for one reason: the perfective past does something unexpected. The infinitive is zapomenout and the present is zapomenu, both with a clean -en-, yet the past is zapomněl — with a soft -mně- cluster that comes out of nowhere if you only know the infinitive. Get that shift right and the rest of the verb is straightforward. The two halves divide labour as usual: perfective zapomenout is a single act of forgetting; imperfective zapomínat is forgetting as a habit or a process.
The two halves, side by side
The perfective zapomenout is Class II, the -nou- / -ne- type (like tisknout, minout): the -nou- of the infinitive becomes -ne- in the present, with endings -u, -eš, -e, -eme, -ete, -ou. The imperfective zapomínat is a regular Class V (-á-) verb on the long stem zapomín-.
| Person | zapomínat (impf.) — present | zapomenout (pf.) — future meaning |
|---|---|---|
| já | zapomínám | zapomenu |
| ty | zapomínáš | zapomeneš |
| on / ona / ono | zapomíná | zapomene |
| my | zapomínáme | zapomeneme |
| vy | zapomínáte | zapomenete |
| oni | zapomínají | zapomenou |
The -mně- in the past
Here is the irregular heart of the verb. The perfective past does not follow the infinitive's spelling. You might expect zapomenul from zapomenout, but the real form is zapomněl — the -eno- collapses to a soft -mně-. Watch all the genders:
| Subject | zapomenout (pf.) past | zapomínat (impf.) past |
|---|---|---|
| masc. sg. | zapomněl jsem | zapomínal jsem |
| fem. sg. | zapomněla jsem | zapomínala jsem |
| neut. sg. | zapomnělo | zapomínalo |
| masc. anim. pl. | zapomněli jsme | zapomínali jsme |
| fem. pl. | zapomněly jsme | zapomínaly jsme |
| neut. pl. | zapomněla | zapomínala |
So the perfective past stem is zapomně-, pronounced with that distinctive mň sound. There's no logic to extract here — it's a stem irregularity you simply memorize, and it's worth memorizing because the past is exactly where you'll use zapomenout most ("I forgot..."). The imperfective zapomínal is perfectly regular by contrast.
Úplně jsem zapomněl, že máš dnes narozeniny.
I completely forgot you have a birthday today. (male speaker)
Zapomněla jsem si doma telefon.
I forgot my phone at home. (female speaker)
What the verb governs
"Forget" has three government frames, and the choice carries a real difference in meaning.
1. Bare accusative — forgetting (often physically leaving behind) a concrete thing:
Zapomněl jsem klíče v práci.
I left my keys at work. (male speaker)
2. na + accusative — forgetting about something: an appointment, a task, a fact, a person you've neglected:
Zapomněl jsem na schůzku s doktorem.
I forgot about the appointment with the doctor. (male speaker)
Nezapomeň na mě, až budeš slavný!
Don't forget about me when you're famous!
3. An infinitive — forgetting to do something:
Zapomněl jsem zamknout dveře.
I forgot to lock the door. (male speaker)
The split between bare accusative and na + accusative is the part English speakers stumble over, because English uses one word "forget" with or without "about." A rough guide: if you can swap in "leave behind" (a physical object), Czech tends to take the bare accusative; if you mean "fail to keep in mind" (an event, a duty, a person), it takes na + accusative. With abstract nouns the na version is almost always the safe choice.
The -ne- / -nou- present
Because the perfective present carries future meaning, zapomenu and friends show up wherever you're talking about forgetting later. The endings ride on the -ne- stem: zapomenu, zapomeneš, zapomene, zapomeneme, zapomenete, zapomenou — the same Class II pattern as tisknout → tiskne and minout → mine.
Neboj se, na to nikdy nezapomenu.
Don't worry, I'll never forget that.
Jestli si to nezapíšeš, zapomeneš to.
If you don't write it down, you'll forget it.
The imperative
The perfective imperative zapomeň ("forget it!") is built on the present stem; with the soft ň it's a high-frequency way to tell someone to let something go.
| zapomínat (impf.) | zapomenout (pf.) | |
|---|---|---|
| ty | zapomínej | zapomeň |
| my | zapomínejme | zapomeňme |
| vy | zapomínejte | zapomeňte |
Zapomeň na něj, nestojí ti za to.
Forget about him, he's not worth it.
Nezapomínej brát ty léky.
Don't forget to take those pills.
Notice the negative command nezapomínej uses the imperfective — negative commands strongly prefer the imperfective, so "don't forget (regularly)" is nezapomínej, while a one-off warning may also use the perfective nezapomeň.
Habitual forgetting
The imperfective zapomínat is your verb for the all-too-human habit of forgetting things over and over:
V poslední době pořád zapomínám jména.
Lately I keep forgetting names.
Děda občas zapomíná, kam si dal brýle.
Grandpa sometimes forgets where he put his glasses.
The contrast with the perfective is sharp: zapomínám jména is a recurring tendency, while zapomněl jsem jeho jméno is one specific lapse ("I forgot his name").
Common mistakes
❌ Zapomenul jsem klíče.
Incorrect past form — the perfective past is zapomněl, not zapomenul.
✅ Zapomněl jsem klíče.
I forgot my keys. (male speaker)
The past collapses to the soft -mně- stem: zapomněl, never zapomenul. This is the single most common error with this verb.
❌ Zapomněl jsem o schůzce.
Incorrect preposition — 'forget about' is na + accusative, not o.
✅ Zapomněl jsem na schůzku.
I forgot about the meeting. (male speaker)
English "about" tempts you toward o, but Czech zapomenout takes na + accusative: na schůzku, not o schůzce.
❌ Zítra budu zapomenout. (intended: I'll forget)
Incorrect — perfectives never combine with budu.
✅ Zítra zapomenu. / Na to nezapomenu.
I'll forget tomorrow. / I won't forget that.
The perfective zapomenu is already future. Don't add budu.
❌ Pořád zapomenu, kam jsem to dal. (intended: I keep forgetting)
Incorrect aspect — a habit needs the imperfective.
✅ Pořád zapomínám, kam jsem to dal.
I keep forgetting where I put it.
A recurring habit ("keep forgetting") is imperfective zapomínám; the perfective zapomenu would mean "I will forget."
Key takeaways
- zapomenout = perfective (one lapse, Class II -ne-/-nou-); zapomínat = imperfective (habit, Class V -á-).
- The perfective past is the irregular zapomněl, zapomněla, zapomnělo, zapomněli / zapomněly / zapomněla — soft -mně-, never zapomenul.
- Government: bare accusative (leave a thing behind) vs na
- accusative (forget about something) vs an infinitive (forget to do).
- Perfective present zapomenu = "I will forget"; nezapomenu = "I won't forget." No budu.
- For "keep forgetting / always forget," use the imperfective zapomínám.
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- zapomínat / zapomenout — to forget (aspect pair card)B1 — Side-by-side reference of zapomínat (imperfective) and zapomenout (perfective): two stems, the past zapomněl with -mně-, the na + accusative government, and the everyday Nezapomeň!
- Class II: -ne- Verbs (tisknout, minout)A2 — The -ne- conjugation, built mostly from -nout infinitives — predictable in the present, but full of perfectives whose 'present' actually means the future.
- Class V: -á- Verbs (dělat)A1 — The largest and most regular present class, ending in -á-.
- Aspect Pairs: The Core SystemA2 — How most Czech verbs come as a two-member aspect pair — one imperfective, one perfective — and how to learn, look up, and choose between them.
- pamatovat si / zapamatovat si — to remember, to memorizeB1 — Side-by-side conjugation of the reflexive pair pamatovat si / zapamatovat si: the Class III -ovat present, the dative-reflexive si, and the contrast with vzpomínat si / vzpomenout si (to recall).