The rule you have been using without being told
Icelandic builds adverbs from adjectives with -lega, the way English uses -ly. You already know a dozen of them:
| adjective | adverb | |
|---|---|---|
| öruggur safe | örugglega | definitely |
| líklegur likely | líklega | probably |
| venjulegur usual | venjulega | usually |
| nákvæmur exact | nákvæmlega | exactly |
| nýr new | nýlega | recently |
| skyndilegur sudden | skyndilega | suddenly |
Take the adjective, drop the masculine -ur, add -lega.
| She sings incredibly well. | Hún syngur ótrúlega vel. |
Four more
| adverb | |
|---|---|
| kærlega | dearly, warmly — above all in takk kærlega, thank you very much |
| rosalega | extremely (colloquial, very common in speech) |
| ótrúlega | incredibly |
| sæmilega | reasonably, fairly well |
rosalega and ótrúlega work like mjög — they intensify an adjective: rosalega góður, ótrúlega dýr.
| The food is extremely good. | Maturinn er rosalega góður. |
Two that are not -lega
sjálfsagt of course, naturally and einnig also, too — a more written alternative to líka.
| She speaks Icelandic and also English. | Hún talar íslensku og einnig ensku. |
Your questions are stored by us to improve Elon.io
