Most word-building you have met so far adds something — a suffix (-ing, -un, -ari, -leiki), a prefix, a second root in a compound. Conversion (also called zero-derivation) is the opposite move: you change a word's part of speech with no overt suffix at all, just by lifting the stem into a new role. A verb becomes a noun, an adjective becomes a noun, a noun becomes a verb — and the only outward sign is the new word's gender, declension, and syntax. This page maps Icelandic's conversion routes, with the spotlight on the one that gives the most leverage and that competitors never connect to the verb system: deverbal root nouns built on a strong verb's ablaut grades. The complement to this page is word-formation/nominalisation, which handles the suffixed action nouns in -ing/-un/-leiki; here we cover the nouns made with nothing added.
What conversion is — and why it is "zero"
In English you say a throw and to throw with the same form: noun and verb are identical, and only the syntax tells them apart (a walk / to walk, a kiss / to kiss). Linguists call it conversion or zero-derivation — "zero" because no suffix is added; the derivation is signalled by absence.
Icelandic does it too, but with a difference forced by its grammar: an Icelandic noun and verb cannot be literally identical, because each must wear its own inflection. The noun kast takes a gender (neuter), a definite article (kastið), and case endings (kasts, kasti); the verb kasta takes its conjugation (ég kasta, hann kastaði). So Icelandic conversion takes the bare stem and lets it stand as a noun, with each word-class's inflection doing the rest. The root is shared; the endings diverge.
Þetta var glæsilegt kast hjá honum.
That was a brilliant throw by him. — 'kast' (neuter noun, 'a throw') is the bare stem of the verb 'kasta' ('to throw'), converted with no suffix.
Hann kastaði boltanum yfir völlinn.
He threw the ball across the field. — the verb 'kasta' itself; the noun 'kast' is its stem standing alone.
Route 1: weak-verb stems → neuter nouns
The simplest conversions sit on weak verbs, whose stem does not change vowel. You strip the infinitive ending and the bare stem stands as a (usually neuter) noun naming the action or a single instance of it. This is the closest match to English a throw / to throw.
| Verb | Converted noun | Gender | Meaning of the noun |
|---|---|---|---|
| kasta ('throw') | kast | neuter | a throw; (also) a fit, a spell |
| hoppa ('hop, jump') | hopp | neuter | a hop, a jump |
| kalla ('call') | kall | neuter | a call, a shout |
| svara ('answer') | svar | neuter | an answer |
| dansa ('dance') | dans | masc. | a dance, dancing |
Ég fékk ekkert svar við bréfinu mínu.
I got no answer to my letter. — 'svar' (neuter, 'an answer') converted from the verb 'svara' ('to answer'); the bare stem stands as a noun.
Það var mikill dans á hátíðinni.
There was a lot of dancing at the festival. — 'dans' (masc., 'a dance/dancing') is the bare stem of the weak verb 'dansa' ('to dance'); the stem stands as a noun with no suffix added.
Route 2: strong-verb ablaut grades → root nouns (the centrepiece)
Here is where Icelandic does something English cannot. A strong verb carries several vowel grades across its principal parts — recall the four-part chant bíta – beit – bitu – bitið (see verbs/strong-verbs-overview and verbs/strong-class-1-3). Conversion can reach into that set of grades and lift one of them out to make a noun. The result is a short, often neuter root noun whose vowel is not free: it is one of the verb's own ablaut grades.
The most productive pattern takes the short-vowel grade — the one that appears in the preterite plural and the supine — and freezes it as the noun. Watch how the noun's vowel matches a column of the verb:
| Verb (class) | Principal parts | Root noun | Noun's grade | Meaning |
|---|---|---|---|---|
| bíta (1) | bíta – beit – bitu – bitið | bit (n.) | short i (pret. pl./supine) | a bite |
| grípa (1) | grípa – greip – gripu – gripið | grip (n.) | short i | a grip, a grasp |
| brjóta (2) | brjóta – braut – brutu – brotið | brot (n.) | o (supine) | a break, a fraction, a fragment |
| bjóða (2) | bjóða – bauð – buðu – boðið | boð (n.) | o (supine) | an invitation, an offer, a message |
| taka (6) | taka – tók – tóku – tekið | tak (n.) | a (infinitive grade) | a hold, a grip |
| fljúga (2) | fljúga – flaug – flugu – flogið | flug (n.) / flaug (f.) | u (pl.) / au (sg.) | flight / a rocket |
This is the insight to carry away. The noun does not invent a vowel; it picks a grade off the verb's principal parts. Brot ("a break, a fragment") uses the same o as brotið and braut; bit ("a bite") uses the same short i as bitu and bitið; grip ("a grip") uses the same i as gripu. So the ablaut series you already memorised to conjugate the verb also tells you the shape of the noun. Competitors teach the strong-verb classes as a conjugation chore and the root nouns as unrelated vocabulary; in fact they are the same vowel system paying off twice.
Hann tók fast tak á handriðinu.
He took a firm hold of the railing. — 'tak' (neuter, 'a hold/grip') is the bare strong-verb root of 'taka' ('to take'); note 'tók tak' — the verb and its converted noun side by side.
Það var lítið brot í bollanum.
There was a small chip/crack in the cup. — 'brot' (neuter, 'a break/fragment') carries the same 'o' grade as the supine 'brotið' of 'brjóta' ('to break').
Glímumaðurinn náði góðu gripi á andstæðingnum.
The wrestler got a good grip on his opponent. — 'grip' (neuter, 'a grip', here dative 'gripi') shares the short 'i' of 'gripu/gripið' from 'grípa' ('to grasp').
Hundsbitið var ekki djúpt en það blæddi.
The dog-bite wasn't deep but it bled. — 'bit' (neuter, 'a bite') in the compound 'hundsbit'; same short-'i' grade as 'bitu/bitið' from 'bíta'.
Some strong verbs yield more than one noun, each taken from a different grade — and the grades then carry different meanings. Fljúga "to fly" gives both flug (neuter, "flight", the u-grade) and flaug (feminine, "a rocket/missile", the au-grade of the preterite singular flaug). This is ablaut doing semantic work: the same verb, two vowel grades, two nouns.
Flugið til Akureyrar tók fjörutíu mínútur.
The flight to Akureyri took forty minutes. — 'flug' (neuter, 'flight'), the u-grade noun of 'fljúga'.
Þeir skutu upp flaug í tilraunaskyni.
They launched a rocket as an experiment. — 'flaug' (feminine, 'rocket'), taken from the preterite-singular grade 'flaug' of the same verb 'fljúga'.
Route 3: a longer derivative on the same root — skurður
Not every deverbal noun is a bare root; some take a thin masculine ending -ur (and frequently i-umlaut) while still being transparently the verb's root. The classic is skera ("to cut", class 4: skera – skar – skáru – skorið) → skurður ("a cut, an incision, a ditch"). The noun's u is the supine grade (skorið → skurð-) plus the masculine -ur, and the umlaut of o → u before the ending lands you at skurð-. It sits on the border between pure conversion and suffixation, but the lesson is the same: the noun's vowel comes straight off the verb's ablaut.
Skurðurinn á hendinni greri fljótt.
The cut on the hand healed quickly. — 'skurður' (masc., 'a cut') is the root noun of 'skera' ('to cut'), built on the supine grade 'skorið' with the masculine -ur.
Læknirinn gerði lítinn skurð á húðinni.
The doctor made a small incision in the skin. — same 'skurður'; the medical sense 'incision' (and the agricultural 'ditch') all sit on the one cut-root.
Route 4: adjective → noun (and the weak/strong trick)
Conversion also turns adjectives into nouns. Two patterns dominate. First, a neuter adjective can stand alone as an abstract noun: gott "good (n.)" → "the good thing", illt "bad", fátt "few things". Second — and this is the live, productive one — an adjective can be nominalised by adding the definite article and using the weak declension, naming "the X one(s)": gamall "old" → sá gamli "the old man / the old one", ungur "young" → sú unga "the young woman", ríkur "rich" → hinir ríku "the rich (people)".
Sá gamli sat alltaf í horninu.
The old man always sat in the corner. — the adjective 'gamall' ('old') converted to a noun via the weak form 'gamli' with the demonstrative 'sá'.
Hinir ríku borga sjaldan fullt verð.
The rich rarely pay full price. — 'ríkur' ('rich') nominalised as the weak plural 'ríku' under the article 'hinir'; an adjective standing as a noun.
Það er fátt um fína drætti hjá okkur núna.
Things are pretty thin for us right now (idiom). — 'fátt' is the neuter adjective ('few') converted to a noun ('few things'); a frozen conversion living in a set phrase.
Route 5: noun → verb (denominal verbs)
The reverse direction — verb from a noun — also exists, though here Icelandic usually adds a regular weak conjugation rather than leaving it truly "zero". A noun gains the productive -a weak-verb frame: hamar "hammer" → hamra "to hammer", salt "salt" → salta "to salt". Because the verb ending is overt, this is more conjugational dressing than pure conversion — but the root is shared and the direction is real, so it belongs in the picture.
Þú þarft að salta vatnið áður en þú setur pastað í.
You need to salt the water before you put the pasta in. — the verb 'salta' ('to salt') built on the noun 'salt'; the noun is the source, the -a frame the dressing.
Hann hamraði nagla í vegginn allt kvöldið.
He hammered nails into the wall all evening. — 'hamra' ('to hammer') from the noun 'hamar'; a denominal verb.
English vs Icelandic: same idea, opposite visibility
For an English speaker the concept of conversion is second nature — English converts constantly with identical forms (a run / to run). Two differences bite. First, in Icelandic the noun and verb are never quite identical, because each carries its own inflection; you cannot re-use the verb's infinitive as a noun but must find the stem-based noun (bare stem, a chosen ablaut grade, or a thin -ur form) and learn its gender. The reflex error is treating the infinitive kasta as if it could be the noun, rather than reaching for kast. Second — with no English parallel — the deverbal noun's vowel is governed by the verb's ablaut class. English break / a break keeps the same vowel; Icelandic brjóta gives brot, not *brjót, because the noun takes the o-grade. The instinct "the noun looks like the verb" fails exactly where it matters: the noun looks like one of the verb's principal parts, not its infinitive.
Common Mistakes
❌ Þetta var gott kasta hjá honum.
Wrong form — the noun 'a throw' is the bare stem 'kast' (neuter), not the verb infinitive 'kasta'. Don't reuse the infinitive as a noun.
✅ Þetta var gott kast hjá honum.
That was a good throw by him. — 'kast' is the converted neuter noun; 'kasta' stays the verb.
The number-one transfer error: assuming the verb's infinitive can double as the noun the way English to throw / a throw does. Icelandic needs the stem-based noun (kast), distinctly inflected.
❌ brjót (for 'a break/fragment'), bít (for 'a bite')
Wrong grade — the root noun takes a SHORT ablaut grade off the verb, not the infinitive's: 'brot' (o-grade, cf. brotið) and 'bit' (short-i, cf. bitið). The infinitive vowels brjót-/bít- are not the noun's.
✅ brot, bit
a break / a bite — the nouns carry the supine/plural ablaut grade (brot like brotið, bit like bitið), not the infinitive vowel.
The defining strong-verb-noun mistake: copying the infinitive's vowel into the noun. The noun's vowel is one of the other principal-part grades — usually the short-vowel (supine/preterite-plural) grade.
❌ Hann tók fast taka á handriðinu.
Wrong form — 'a hold' is the root noun 'tak' (neuter), not the infinitive 'taka'. 'tók fast tak' pairs the verb 'tók' with the noun 'tak'.
✅ Hann tók fast tak á handriðinu.
He took a firm hold of the railing. — verb 'tók' + converted noun 'tak'.
❌ Sá gamall sat í horninu.
Wrong declension — a nominalised adjective takes the WEAK form under the article/demonstrative: 'sá gamli' (weak), not the strong 'gamall'.
✅ Sá gamli sat í horninu.
The old man sat in the corner. — 'gamli' is the weak (nominalised) form of 'gamall' standing as a noun.
Adjective-to-noun conversion needs the weak ending after sá/hinn: sá gamli, hinir ríku — not the strong predicative form.
Key Takeaways
- Conversion (zero-derivation) changes a word's part of speech with no suffix — but Icelandic nouns and verbs are never identical, because each takes its own inflection; the root is shared, the endings diverge.
- Weak verbs convert on the bare stem, usually to a neuter noun: kasta → kast ('a throw'), svara → svar ('an answer'), kalla → kall ('a shout').
- Strong verbs are a vowel quarry: the root noun picks an ablaut grade off the principal parts — bíta → bit, grípa → grip (short i), brjóta → brot, bjóða → boð (the o-grade), taka → tak (the a-grade). One verb can yield two nouns from two grades: fljúga → flug (flight) and flaug (rocket).
- A thin masculine -ur
- umlaut gives root nouns like skera → skurður ('a cut'); adjectives nominalise via the neuter (gott) or the weak form under an article (sá gamli, hinir ríku); nouns → verbs add the -a frame (salt → salta).
- The defining error is using the infinitive's vowel for the noun (*brjót, *kasta). The noun copies a principal part, not the infinitive — so the strong-verb classes you already know hand you the noun's vowel for free.
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Start learning Icelandic→Related Topics
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- Strong Verbs and Ablaut: OverviewA2 — The strong verb system: verbs that build the past by changing their stem vowel (ablaut) instead of adding an ending, with FOUR principal parts — infinitive, preterite singular, preterite plural, supine — and the crucial split where the past singular and past plural can carry different vowels (fann vs fundu).
- I-Umlaut as a Sound AlternationB1 — I-umlaut (i-hljóðvarp) is an older fronting alternation frozen into Icelandic paradigms: a lost i or j in the next syllable pulled the stem vowel forward — a→e, o→y, u→y, á/ó→æ, ú→ý, au→ey. It explains maður→menn, fótur→fætur, stór→stærri, ungur→yngri. Unlike u-umlaut it is no longer productive, so you memorise the affected sets — but the same alternation links surprising word-families.
- Strong Verb Classes 1-3B1 — The first three ablaut classes of Icelandic strong verbs and their vowel series: Class 1 (í–ei–i–i: bíta → beit, bitu, bitið), Class 2 (jó/jú–au–u–o: bjóða → bauð, buðu, boðið), and Class 3 (e/i–a–u–o: verða → varð, urðu, orðið; finna → fann, fundu) — including some of the highest-frequency verbs in the language.