A prefix sits at the front of a word and reshapes its meaning without changing its part of speech: þarfur "necessary" plus ó- gives óþarfur "unnecessary"; taka "take" plus endur- gives endurtaka "repeat." The reason prefixes are worth a page of their own is that they are decodable: once you know that endur- means "re-" and van- means "under-/mis-", you can crack open hundreds of words you have never met and often coin new ones correctly. This page is a reference catalogue of the prefixes that are genuinely productive in modern Icelandic. It deepens the broader Derivation page — which introduces ó- as the great vocabulary-doubler — by laying out the full set side by side; for the suffixes (-legur, -laus, -skapur…) see the companion Suffix Catalogue. The headline insight: most Icelandic prefixes line up almost one-to-one with an English or Latin prefix, so learning the mapping turns a wall of long compounds into something you can read.
The catalogue at a glance
| Prefix | Meaning | English analogue | Example |
|---|---|---|---|
| ó- | negation, "not" | un-, in-, dis- | óþarfur "unnecessary" |
| and- | counter, against, response | anti-, counter- | andstæða "opposite" |
| endur- | again, restore | re- | endurtaka "repeat" |
| van- | under-, mis-, deficient | under-, mis-, mal- | vanmeta "underestimate" |
| sam- | together, joint, co- | co-, con-, syn- | samvinna "cooperation" |
| for- | fore-, pre-, ahead | fore-, pre- | forseti "president" |
| mis- | wrongly, amiss, differing | mis- | misskilja "misunderstand" |
| gagn- | counter, through, mutual | counter-, through- | gagnrýni "criticism" |
ó- — negation
ó- is the negation prefix, the Icelandic un-/in-/dis-. It attaches to an adjective, noun, or adverb and flips it to its opposite — and it is fully productive, the single most useful prefix in the language. The Derivation page treats it as a vocabulary-doubler for adjectives (þægilegur → óþægilegur); here, note that it negates nouns just as freely: þörf "need" → óþarfi "something unnecessary," réttlæti "justice" → óréttlæti "injustice." The accent is part of the prefix — it is always ó-, never bare o-.
Þú þarft ekki að borga — þetta er algjör óþarfi.
You don't have to pay — this is completely unnecessary. (þörf 'need' → óþarfi 'an unnecessary thing'; adj. óþarfur 'unnecessary')
Það er hróplegt óréttlæti hvernig farið var með hana.
It's a glaring injustice how she was treated. (réttlæti 'justice' → óréttlæti 'injustice')
and- — counter, against, response
and- marks opposition or response — "against, counter-, anti-, reply." It is the same root as anda "to breathe" and andi "spirit/breath," but as a prefix it means "facing the other way." English anti-/counter- is the closest map.
| Base |
| Meaning |
|---|---|---|
| staða "position" | andstæða | opposite, antithesis |
| svar "answer" | andsvar | rejoinder, counter-reply |
| rúm "space" | andrúmsloft | atmosphere (lit. "counter-space air") |
Hugrekki er andstæða hugleysis.
Courage is the opposite of cowardice. (and- + staða → andstæða 'opposite/antithesis')
Það var góð stemning og afslappað andrúmsloft í salnum.
There was a good vibe and a relaxed atmosphere in the hall. (and- in andrúmsloft 'atmosphere')
endur- — again, re-
endur- is the Icelandic re-: do it again, do it back, restore. It is highly productive and lines up almost perfectly with English re-, so endur- + a verb you know usually means exactly what re- + the English verb would.
| Base |
| Meaning |
|---|---|---|
| taka "take" | endurtaka | repeat (re-take) |
| vinna "work / win" | endurvinna | recycle (re-process) |
| greiða "pay" | endurgreiða | refund (re-pay) |
Gætirðu endurtekið þetta? Ég náði ekki alveg.
Could you repeat that? I didn't quite catch it. (endur- + taka → endurtaka 'repeat')
Við flokkum og endurvinnum allt plast á heimilinu.
We sort and recycle all our plastic at home. (endur- + vinna → endurvinna 'recycle')
van- — under-, mis-, deficient
van- signals deficiency or going wrong — "under-, mis-, mal-, lacking." This one is worth dwelling on because learners routinely fail to parse it: vanmeta is not a mysterious lexical item, it is transparently van- ("under") + meta ("value/assess") = "undervalue, underestimate." Once you see van- as "under-/mis-", a cluster of words opens up.
| Base |
| Meaning |
|---|---|---|
| meta "to value, assess" | vanmeta | underestimate, undervalue |
| þekking "knowledge" | vanþekking | ignorance (lack of knowledge) |
| rækja "to tend, cultivate" | vanrækja | neglect |
Ekki vanmeta hana — hún er klárari en hún lætur.
Don't underestimate her — she's sharper than she lets on. (van- 'under' + meta 'assess' → vanmeta)
Hann hefur vanrækt heilsuna sína í mörg ár.
He's neglected his health for years. (van- 'mis-/deficient' + rækja 'tend' → vanrækja 'neglect')
sam- — together, joint, co-
sam- means "together, joint, shared" — the Icelandic co-/con-/syn-. It is the same element as samur "same" and saman "together," and it is enormously productive: stick sam- on a noun or verb and you get the "joint / mutual / co-" version.
| Base |
| Meaning |
|---|---|---|
| vinna "work" | samvinna | cooperation (working together) |
| starf "job, work" | samstarf / samstarfsmaður | collaboration / co-worker |
| félag "society, association" | samfélag | community, society (a "co-society") |
Þetta verkefni krefst góðrar samvinnu allra deilda.
This project requires good cooperation from all departments. (sam- 'together' + vinna 'work' → samvinna)
Hún er besti samstarfsmaður sem ég hef haft.
She's the best co-worker I've ever had. (sam- + starf 'work' → samstarfsmaður 'co-worker')
for- — fore-, pre-, ahead
for- is "fore-, pre-, ahead, chief" — temporal precedence or seniority, exactly like English fore-/pre-. Forseti "president" is literally a "fore-sitter" (the one who sits at the head); forsaga is the "pre-history / back-story" of a matter.
| Base |
| Meaning |
|---|---|---|
| seti "sitter" | forseti | president (fore-sitter) |
| saga "story, history" | forsaga | back-story, prehistory |
| maður "man, person" | formaður | chairman (lead person) |
Til að skilja deiluna þarftu að þekkja forsögu málsins.
To understand the dispute you need to know the back-story of the matter. (for- 'pre-' + saga 'story' → forsaga)
mis- — wrongly, amiss
mis- means "wrongly, amiss, differing" — and it is the same mis- as in English misunderstand, misuse. Misskilja is transparently mis- + skilja ("understand") = "misunderstand." It also carries a "differing / unequal" sense (misjafn "varying, uneven").
| Base |
| Meaning |
|---|---|---|
| skilja "understand" | misskilja | misunderstand |
| nota "use" | misnota | misuse, abuse |
| jafn "equal, even" | misjafn | varying, uneven, mixed |
Fyrirgefðu, ég held að þú hafir misskilið mig.
Sorry, I think you've misunderstood me. (mis- 'wrongly' + skilja 'understand' → misskilja)
Gæði þjónustunnar eru frekar misjöfn.
The quality of the service is rather uneven. (mis- 'differing' + jafn 'equal' → misjafn 'varying')
gagn- — counter, through, mutual
gagn- is built on gagn ("use, benefit") and the directional gegn ("against, through"). As a prefix it means "counter-, against, through, mutual." Its most important derivative is gagnrýni "criticism" — literally a "counter-examination" — and the verb gagnrýna "to criticise."
| Base |
| Meaning |
|---|---|---|
| rýni "scrutiny" | gagnrýni | criticism, critique |
| kvæmur "passable" (root) | gagnkvæmur | mutual, reciprocal |
| sær "see-through" (root) | gagnsær | transparent (see-through) |
Hann tók gagnrýninni vel og lagaði verkefnið.
He took the criticism well and fixed the project. (gagn- 'counter' + rýni 'scrutiny' → gagnrýni)
Virðingin á milli þeirra er gagnkvæm.
The respect between them is mutual. (gagn- 'mutual' → gagnkvæmur 'reciprocal')
English vs Icelandic: the prefixes line up
The reason this catalogue is worth memorising is the near one-to-one mapping onto prefixes you already know. endur- is re-, van- is under-/mis-, mis- is mis-, sam- is co-/con-, for- is fore-/pre-, and- is anti-/counter-, gagn- is counter-/through-, ó- is un-/in-. The differences are small but real. First, Icelandic prefers a native prefix where English often borrows a Latin one — Icelandic builds samvinna ("co-operation") from home parts, where English imports co- + operate. Second, the Icelandic prefix attaches solidly, with no hyphen (endurtaka, vanmeta, samvinna), except ó- which keeps its accent in every form. And third, the base after the prefix is usually a transparent, recognisable Icelandic word, so the decode is reliable: see the prefix, strip it, read the root.
Common Mistakes
❌ Hann hefur metið stöðuna van.
A prefix is not a separable word — van- attaches to the front: hann hefur vanmetið stöðuna.
✅ Hann hefur vanmetið stöðuna.
He has underestimated the situation.
These prefixes are bound — they attach solidly to the front of the word (vanmeta), never trail behind it as a separate particle.
❌ Ég held að þú hafir mis skilið mig.
No space — mis- joins solidly to its base: misskilið.
✅ Ég held að þú hafir misskilið mig.
I think you've misunderstood me.
Icelandic prefixes are written solid, with no space and no hyphen: misskilja, endurtaka, samvinna. (Note the double s in misskilja: mis- + skilja.)
❌ Þetta er algjör oþarfi.
Lost accent — the negation prefix is ó-, always with the acute: óþarfi.
✅ Þetta er algjör óþarfi.
This is completely unnecessary.
ó- always carries its accent. Dropping it (*oþarfi) is a spelling error — ó and o are different letters.
❌ Þeir hafa gott vinna saman á verkefninu.
Missed prefix — 'cooperation' is the derived noun samvinna, not 'vinna saman' used as a noun: góða samvinnu.
✅ Þeir hafa átt í góðri samvinnu á verkefninu.
They've had good cooperation on the project.
When you want the noun "cooperation," reach for the sam- derivative samvinna, not a loose verb phrase. Recognising that sam- + vinna gives you a ready-made noun is the productive payoff.
❌ Ég ætla að gera prófið aftur — ég endur-tek það.
No hyphen in the prefix, and the verb is just endurtaka: ég endurtek það.
✅ Ég ætla að taka prófið aftur og endurtek efnið vel fyrir það.
I'm going to retake the exam and review the material well for it.
endur- attaches without a hyphen: endurtaka, endurtek. (And to "retake an exam" Icelandic says taka prófið aftur; endurtaka leans toward "repeat/redo.")
Key Takeaways
- ó- = negation (un-/in-), fully productive on adjectives and nouns (óþarfi, óréttlæti) — keeps its accent always.
- and- = counter/against (andstæða "opposite," andrúmsloft "atmosphere").
- endur- = re- (endurtaka "repeat," endurvinna "recycle," endurgreiða "refund") — maps perfectly onto English re-.
- van- = under-/mis- (vanmeta "underestimate," vanrækja "neglect") — strip it and read the root.
- sam- = co-/together (samvinna "cooperation," samfélag "community," samstarfsmaður "co-worker").
- for- = fore-/pre- (forseti, forsaga); mis- = mis- (misskilja, misnota); gagn- = counter-/through- (gagnrýni "criticism," gagnsær "transparent").
- All attach solidly (no hyphen, no space); learn the prefix→meaning map and you can decode and coin words on sight.
Now practice Icelandic
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Start learning Icelandic→Related Topics
- Derivation: Prefixes and SuffixesB1 — The productive derivational affixes of Icelandic — agent -ari, abstract -ing/-un/-leiki/-skapur, adjective-forming -legur/-laus/-samur, and the prefixes ó- (negation), and- (counter-), endur- (re-), van- (mis-/under-), for-/frum- — with the headline insight that ó- productively negates almost any adjective, doubling your vocabulary.
- Suffix Catalogue: -legur, -laus, -samur, -leiki, -skapurB1 — A working catalogue of the productive Icelandic derivational suffixes — adjective-makers -legur ('-ly/-ish': vinalegur 'friendly'), -laus ('-less': atvinnulaus 'unemployed'), -samur ('-some/prone to': friðsamur 'peaceable'), -ugur (grösugur 'grassy'); and noun-makers -leiki/-leikur (abstract: kærleikur 'love'), -skapur (abstract/collective: vinskapur 'friendship'), -ari (agent: kennari 'teacher'), -ing/-un (deverbal) — each paired with its English analogue and tagged for the resulting word class.
- Compounding: The Core Word-Building EngineB1 — How Icelandic compounds are built structurally — a determinant (first element) modifies a head (last element), the head fixes gender and inflection, and the elements join with a bare link, a genitive -s link, or a genitive plural -a link (sólskin, landsbanki, barnabók), often encoding a hidden grammatical relationship you can read off.
- Nominalisation: Making Nouns from Verbs and AdjectivesB2 — How Icelandic builds nouns out of verbs and adjectives. Deverbal nouns in -ing/-un name the action (bygging 'building', skoðun 'examination'); the -andi present participle nominalises as an agent (nemandi 'student', stjórnandi 'director'); and DEADJECTIVAL abstracts in -leiki/-d/-t/-ð name the quality (fegurð 'beauty', hæð 'height', lengd 'length'). The headline insight: deadjectival abstracts systematically trigger i-umlaut (hár→hæð, langur→lengd, breiður→breidd, djúpur→dýpt) — the very same vowel change as the comparative — so the abstract noun and the comparative share a vowel. Build native nouns instead of importing English '-tion' words.
- Negative Words: enginn, ekkert, aldrei, hvergiB1 — Icelandic's negative quantifiers and adverbs — enginn 'no one/no', ekkert 'nothing', aldrei 'never', hvergi 'nowhere', engan veginn 'by no means' — and the rule that standard Icelandic avoids double negation, plus the enginn ↔ ekki neinn alternation.