Adjectives (lýsingarorð) are the words that describe things, such as interesting, funny, and difficult.
Adjectives need to have the same gender, case, and number as the noun they describe. For that reason, adjectives has far more possible declensions than nouns, there is a different one for each gender it describes.
Adjectives also exist in three different forms based on whether they are comparing things (degree of comparison):

The regular form,[a] such as “good”

The form you use when comparing things (comparative form),[b] such as “better”

The form when something the greatest or most of something (superlative form),[c] such as “best”

There is yet another thing that complicates adjectives. They have two different conjugation forms:
  • Strong declension. Exists for the regular form (“good”) and the superlative form (“best”), but not the comparative form (“better”). This is the default declension form of the the regular form of adjectives.
    • hér er góður maður – Ends in a consonant, this is a strong declension.
  • Weak declension. Exists for all three degrees of comparison (regular (“good”), comparative (“better”), and superlative (“best”)). For the regular form, this usually happens because the noun has a definite article.
    • hér er góði maðurinn – Ends in a vowel in this case and in all cases, this is a weak declension.

Parts of speech: NounsPronounsAdjectivesVerbsAdverbsPrepositions • Conjuctions • Interjections