Norwegian adjective exceptions

If the adjective ends in -ig, it does not take -t.

et nødvendig onde (a necessary evil)

et vanskelig barn (a dificult child)

N.B. the -g in -ig is not pronounced.

Most adjectives ending in -sk do not take -t.

et norsk flagg

et engelsk hus

Adjectives ending in a stressed vowel take double -tt.

ny - nytt, et nytt hus

blå - blått, et blått skjerf

fri - fritt, et fritt folk

*Hvit takes an extra -t, et hvitt hus.*

The three exceptional situations above take -e in the plural.

to vanskelige barn

to norske flagg

to nye hus

Some adjectives like the colours oransje, lilla, rosa always keep the same form.

et oransje fly - to oransje fly 

et lilla skjerf - to lilla skjerf

et rosa skjørt - to rosa skjørt

Other adjectives that do not change are: moderne, stille, levende, spennende, stakkars, avsides, gratis, feil

et moderne hus - to moderne hus,

et gratis bilde - to gratis bilder

Adjectives ending in -el, -en, -er dropp the -e and a double consonant is reduced to a single one.

en gammel mann - et gammelt hus -  to gamle menn - to gamle hus - to gamle hus

en skummel gate - et skummelt hus - to skumle menn  (skummel - scary)

en vakker hund - et vakkert barn - to vakre barn