The Middle Voice overview explained what an -st verb means; this page is purely about how to build the forms. The good news is that there is no separate paradigm to memorise — an -st verb is just an ordinary verb with -st glued onto the end of each conjugated form. The catch is that gluing -st on triggers a handful of predictable collisions and assimilations: the present -r of the 2nd and 3rd person disappears, the 1st person often loses its ending, and the preterite welds a dental consonant (-ð-/-t-) to the -st. Learn those four mechanical adjustments and you can conjugate any middle-voice verb you meet.
The base rule: -st goes on last, then things collide
Mechanically, -st is the very last thing on the verb — it sits after the personal ending. But Icelandic does not tolerate the cluster -rst in these forms, so the personal -r of the present 2sg/3sg is dropped before -st lands. That single deletion is the whole reason the middle voice looks irregular at first.
Present tense: the singular merges
Here is the headline fact about the middle-voice present. In the active voice, the three singular persons are usually distinct (ég klæði, þú klæðir, hann klæðir). In the middle voice they merge into a single form, because the distinguishing -r has been deleted and the 1sg often loses its ending too. So klæðist means both "you dress" and "he dresses" — and frequently "I dress" as well. This is a genuine middle-voice syncretism: one form, three persons.
Take the weak verb setjast "to sit down" (the middle of setja). Its active 3sg is setur; drop the -r, add -st, and the t + st assimilate to give sest — identical for ég, þú, and hann:
| Person | Present (nútíð) | Preterite (þátíð) |
|---|---|---|
| ég | sest | settist |
| þú | sest | settist |
| hann / hún / það | sest | settist |
| við | setjumst | settumst |
| þið | setjist | settust |
| þeir / þær / þau | setjast | settust |
Ég sest alltaf aftast í strætó.
I always sit at the back of the bus. (1sg sest)
Sestu hérna hjá mér, það er nóg pláss.
Sit down here next to me, there's plenty of room. (imperative sestu)
Hún sest niður og fær sér kaffi á hverjum morgni.
She sits down and has a coffee every morning. (3sg sest — same form as the 1sg)
Notice the plural restores the personal endings around the -st: setjumst (við), setjist (þið), setjast (þeir). The -st never disappears, but in the plural it simply rides on top of the normal -um / -ið / -a endings.
Now the strong verb komast "to manage to get (somewhere)" (the middle of koma). Its active present singular is kem / kemur / kemur; delete the -r, add -st, and all three singulars become kemst:
| Person | Present (nútíð) | Preterite (þátíð) |
|---|---|---|
| ég | kemst | komst |
| þú | kemst | komst |
| hann / hún / það | kemst | komst |
| við | komumst | komumst |
| þið | komist | komust |
| þeir / þær / þau | komast | komust |
Ég kemst ekki á æfingu í kvöld, ég er með hálsbólgu.
I can't make it to practice tonight, I have a sore throat. (1sg kemst)
Kemst þú á fundinn klukkan tvö?
Can you make it to the meeting at two? (2sg kemst — same shape as 1sg/3sg)
Við komumst loksins heim eftir miðnætti.
We finally got home after midnight. (1pl komumst)
Why English speakers find the merge disorienting
English keeps "I / you / he" apart with separate pronouns but barely touches the verb ("I sit, you sit, he sits" — only the -s moves). So an English speaker is used to the pronoun carrying the load and the verb staying nearly constant. Icelandic active verbs do the opposite — the ending usually tells you the person. The middle voice then removes that ending in the singular, throwing the burden back onto the pronoun. The practical upshot: in sest and kemst the pronoun is doing all the work, exactly as in English, which is unusual for Icelandic and feels deceptively easy until you try to produce the plural and forget to put the endings back.
Preterite: stack a dental + -st
The preterite is where most learners stumble. You do not simply add -st to the active past. Instead the middle preterite takes the past stem, adds the weak dental suffix (-ð- or -t-) — or, in a strong verb, uses the bare strong past — and then welds -st on, with assimilation cleaning up the cluster.
For a weak verb like setjast, the active past is setti (a -t- preterite). The middle stacks that dental and -st together and the t's collapse: sett- + -ist → settist. The result is the chain dental + -st, pronounced as a tidy -tist / -ðist:
| Active past | Dental | Middle preterite |
|---|---|---|
| setti (setja) | -t- | settist |
| klæddi (klæða) | -dd- | klæddist |
| opnaði (opna) | -að- | opnaðist |
| hitti (hitta) | -t- | hittist |
Hún klæddist svörtu á jarðarförinni.
She wore black at the funeral. (klæðast, past klæddist — dental dd + st)
Við settumst niður og ræddum málin í ró og næði.
We sat down and discussed things at our leisure. (1pl past settumst)
Þau hittust fyrst á tónleikum árið 2019.
They first met at a concert in 2019. (hittast, past hittust)
For a strong verb like komast, there is no dental at all — the strong past stem already carries the tense, and you just add -st: kom + -st → komst. Watch the plurals: the 1pl is komumst (not komstum), and the 3pl is komust. The single most common learner error here is metathesising the -um- and the -st-.
Ég komst loksins að sannleikanum.
I finally found out the truth. (komast að, past komst)
Þau komust ekki út úr bænum fyrr en eldsnemma.
They couldn't get out of town until the crack of dawn. (3pl past komust)
The supine: also ends in -st
The supine — the form you use after hafa in the perfect — likewise carries -st. It is built on the ordinary supine plus the middle ending: komið → komist, séð → sést, sett → sest. So the perfect of a middle verb is hafa + an -st supine: ég hef komist, við höfum sést, hún hefur sest.
Við höfum ekki sést í mörg ár.
We haven't seen each other in years. (perfect: höfum + supine sést)
Ég hef aldrei komist svona nálægt hval.
I've never gotten this close to a whale. (perfect: hef + supine komist)
Common Mistakes
❌ Hann klæðistr alltaf vel.
Incorrect — the -st deletes the present -r; never write -str. It is klæðist.
✅ Hann klæðist alltaf vel.
He always dresses well.
The cluster -rst is not allowed in these forms. The personal -r is deleted before -st attaches, which is exactly why the 2sg and 3sg merge.
❌ Ég settst niður.
Incorrect — the weak middle preterite inserts the dental: settist, not *settst.
✅ Ég settist niður.
I sat down.
A weak -st verb stacks its dental suffix (setti → sett-) before the -st. Dropping the dental and welding the bare stem to -st gives the unpronounceable settst.
❌ Þú kemstur ekki inn án miða.
Incorrect — the middle present takes no personal -ur; it is just kemst for þú.
✅ Þú kemst ekki inn án miða.
You can't get in without a ticket.
Because -st has already swallowed the -r, there is no separate þú ending to add. The 2sg is identical to the 1sg and 3sg: kemst.
❌ Við komstum heim seint.
Incorrect — the strong middle past plural is komumst, not the metathesised *komstum.
✅ Við komumst heim seint.
We got home late.
In the plural the personal endings come back around the -st: 1pl kom-um-st. Don't shuffle the -um- and -st- into komstum.
❌ Ég hef komið heim í öllum veðrum.
Wrong verb — the perfect of komast keeps the -st supine: hef komist.
✅ Ég hef komist heim í öllum veðrum.
I've managed to get home in all kinds of weather.
The supine carries -st too. Komið is the supine of plain koma "come"; komist is the supine of komast "manage to get."
Key Takeaways
- An -st verb is its base verb plus -st on every finite form — but the -st triggers predictable collisions.
- Present: the -r of the 2sg/3sg is deleted, so the three singular persons merge (sest = ég/þú/hann, kemst = ég/þú/hann). The plural restores the endings around -st (setjumst, setjist, setjast).
- Preterite (weak): stack the dental + -st (setti → settist, klæddi → klæddist, opnaði → opnaðist).
- Preterite (strong): add -st to the strong past stem (kom → komst); plurals are komumst / komust, never komstum.
- Supine also ends in -st (komist, sést, sest), so the perfect keeps it: ég hef komist.
Now practice Icelandic
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Start learning Icelandic→Related Topics
- The Middle Voice (-st): OverviewB1 — An orientation to the Icelandic middle voice — the verb form built by suffixing -st — covering its four meaning-types (reflexive, reciprocal, anticausative/passive-like, and lexicalised) and the crucial fact that the meaning of an -st verb is not predictable from its base, so many are their own dictionary entries.
- 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.
- Reciprocal and Anticausative -stB2 — The two most productive jobs of the -st middle voice: the reciprocal ('each other' — hittast, sjást, kyssast, berjast) and the anticausative ('happen by itself' — opnast, lokast, breytast). How the reciprocal folds in English 'each other' and the anticausative detransitivises a verb, plus why the anticausative is Icelandic's natural alternative to a passive for events with no agent.
- komast (to manage to get somewhere)B1 — Full conjugation of komast (kemst / komst / komust / komist), the lexicalised middle of koma meaning 'manage to get / reach', with the -st paradigm, the idiom komast að 'find out', the motion sense komast heim / komast í, and the crucial point that the -st adds 'succeed in' — komast ≠ plain koma.
- setjast (to sit down)B1 — Full conjugation of setjast (sest / settist / settumst / sest), the middle voice of setja, meaning 'sit oneself down' — a dynamic change of posture, in contrast with the static sitja 'be sitting'. Covers the -st preterite settist/settumst, directional setjast niður, and the setjast/sitja change-of-state distinction.