Learn Icelandic: Konan er gömul en kennarinn er nýr. - The woman is old but the teacher is new.

Adjectives in Icelandic change to match the gender of the noun they describe. Because konan (the woman) is a feminine noun, we must use the feminine singular form of the adjective, which is gömul.

Why does the first vowel change from "a" in gamall to "ö" in gömul?

This is due to a very common Icelandic vowel change called the U-shift. When forming the feminine version of certain adjectives, an a in the root word shifts to an ö. This is why the masculine gamall becomes the feminine gömul.

Why does nýr (new) end in an -r?

Kennarinn (the teacher) is a masculine noun. When an adjective describes a masculine noun in the basic subject form (the nominative case), it typically takes the masculine ending -r.

How can I tell that kennarinn is masculine and konan is feminine just by looking at the words in this sentence?

You can spot the gender by looking at the attached "the" at the end of the words! The ending -inn on kennarinn is the masculine definite article. The ending -n on konan is the feminine definite article. Recognizing these noun endings helps you know whether to use the masculine or feminine form of your adjectives.