gleyma ("to forget") is conjugated as smoothly as any regular weak verb — gleymi, gleymdi, gleymt, no vowel surprises — and yet it is one of the easiest verbs to get wrong, because its object is in the dative, not the accusative. You forget to something, structurally speaking: gleyma lyklunum ("forget the keys"), where lyklunum is dative. English gives you no warning at all, since "forget the keys" looks like a plain direct object. This page drills the dative, the gleyma að + infinitive pattern, and the clean contrast with its opposite, muna ("remember"), which takes the accusative instead.
Conjugation
Class: weak, Class 2 (the -di preterite). Auxiliary: hafa — ég hef gleymt "I have forgotten." The stem gleym- is stable throughout; only the endings change.
| Principal parts | |
|---|---|
| Infinitive | að gleyma |
| 1sg present | gleymi |
| 1sg past | gleymdi |
| Supine | gleymt |
| Person | Present (nútíð) | Past (þátíð) |
|---|---|---|
| ég | gleymi | gleymdi |
| þú | gleymir | gleymdir |
| hann / hún / það | gleymir | gleymdi |
| við | gleymum | gleymdum |
| þið | gleymið | gleymduð |
| þeir / þær / þau | gleyma | gleymdu |
| Person | Present subjunctive | Past subjunctive |
|---|---|---|
| ég | gleymi | gleymdi |
| þú | gleymir | gleymdir |
| hann / hún / það | gleymi | gleymdi |
| við | gleymum | gleymdum |
| þið | gleymið | gleymduð |
| þeir / þær / þau | gleymi | gleymdu |
| Non-finite & imperative | |
|---|---|
| Imperative (þú) | gleymdu |
| Imperative (þið) | gleymið! |
| Supine | gleymt |
| Past participle (m/f/n) | gleymdur / gleymd / gleymt |
| Middle voice (miðmynd) | gleymast — "to be forgotten / slip one's mind" |
The dative object: gleyma einhverju
This is where English speakers fail by reflex. In English, "forget" takes an ordinary direct object: forget the keys, forget the meeting, forget your name. In Icelandic, gleyma governs the dative — gleyma einhverju ("forget something," dative). So the keys, which in the nominative are lyklarnir and in the accusative lyklana, appear here as lyklunum (dative plural). There is no logic to recover from English; you simply have to mark gleyma in your memory as "dative verb" and decline the object accordingly.
Ég gleymdi lyklunum heima.
I forgot the keys at home.
Ekki gleyma afmælinu hennar á morgun!
Don't forget her birthday tomorrow!
Hann hafði alveg gleymt fundinum.
He had completely forgotten the meeting.
gleyma að + infinitive — "forget to do something"
To say you forgot to do something, use gleyma að + infinitive. Here there is no dative noun to worry about — the að-clause is the object — so this pattern feels reassuringly like English "forget to."
Ég gleymdi að senda tölvupóstinn.
I forgot to send the email.
Gleymdu ekki að loka glugganum.
Don't forget to close the window.
gleyma sér — "lose track of oneself"
The reflexive gleyma sér ("forget oneself") means to get so absorbed in something that you lose track of time or surroundings — a lovely everyday idiom with no neat English one-word equivalent.
Ég gleymdi mér alveg í bókinni og missti af strætó.
I lost all track of time in the book and missed the bus.
The middle voice: gleymast
The -st form gleymast makes the thing forgotten the subject: "to be forgotten, to slip one's mind." The dative person to whom it slips is optional: mér gleymdist að hringja "it slipped my mind to call" (literally "to-me it-was-forgotten to call").
Þetta lag má aldrei gleymast.
This song must never be forgotten.
Mér gleymdist alveg að hringja í þig — fyrirgefðu!
It completely slipped my mind to call you — sorry!
gleyma vs. muna — opposite meanings, opposite cases
The neat trap: gleyma ("forget") takes the dative, but its antonym muna ("remember") takes the accusative. So the same noun changes case depending on which verb you choose — ég man nafnið ("I remember the name," accusative) but ég gleymdi nafninu ("I forgot the name," dative). Learn the pair together so the contrast sticks.
Ég man nafnið en gleymdi símanúmerinu.
I remember the name but forgot the phone number.
Common Mistakes
❌ Ég gleymdi lyklana.
Incorrect — gleyma takes the dative, so 'the keys' is lyklunum, not the accusative lyklana
✅ Ég gleymdi lyklunum.
I forgot the keys.
❌ Ekki gleyma fundinn.
Incorrect — the object must be dative: fundinum, not the accusative fundinn
✅ Ekki gleyma fundinum.
Don't forget the meeting.
❌ Hún gleymaði nafninu mínu.
Incorrect — gleyma is a Class-2 verb with a -di past (gleymdi), not a regularised -aði
✅ Hún gleymdi nafninu mínu.
She forgot my name.
❌ Ég gleymdi að senda póstinum.
Incorrect — the object of senda here is accusative (póstinn); don't spread gleyma's dative onto the inner verb
✅ Ég gleymdi að senda póstinn.
I forgot to send the mail.
Key Takeaways
- gleymi / gleymir / gleymdi / gleymt — a regular weak Class-2 verb with a -di preterite and a stable stem.
- The headline rule: gleyma takes a DATIVE object — gleyma lyklunum, afmælinu, fundinum.
- gleyma að
- infinitive = "forget to do"; gleyma sér = "get absorbed, lose track of oneself."
- Middle voice gleymast = "be forgotten / slip one's mind" (often with a dative person: mér gleymdist).
- Contrast with muna (remember), which takes the accusative — opposite meaning, opposite case.
- Auxiliary is hafa: ég hef gleymt.
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- muna (to remember)A2 — Full conjugation of the irregular preterite-present verb muna (man / manst / mundi / munað), with its endingless present man, the accusative object (muna eitthvað), muna eftir + dative 'recall', and the all-important contrast with munu 'shall/will'.
- The Weak Preterite: -aði, -di, -ði, -tiA2 — How to choose and form the weak past tense — Class-1 -a verbs take -aði (tala → talaði, plural töluðum), Class-2 verbs take the short dental -di/-ði/-ti picked by the preceding sound (reyndi, dæmdi, keypti) — with the full tala paradigm and the 'when in doubt, -aði' default for unknown verbs.