Learn Icelandic: Gott kvöld! Maturinn er góður. - Good evening! The food is good.

In Icelandic, describing words (adjectives) change their endings to match the gender of the noun they describe. Kvöld (evening) is a neuter word, so it uses the neuter form gott. Matur (food) is a masculine word, so it uses the masculine form góður.

Why is "the food" written as one word, maturinn?

Instead of putting a separate word for "the" in front of a noun like we do in English, Icelandic attaches it to the end of the word. The base word for food is matur. Adding the masculine ending -inn gives you maturinn (the food).

How can I tell that matur is a masculine word?

There are three great clues right in this sentence! The base noun matur ends in -ur, which is a very common ending for masculine words. The attached "the" ending -inn is specifically for masculine words, and the describing word góður ends in -ur to match a masculine noun.

Could I say Maturinn er gott if I forget the gender?

People would understand you, but it is grammatically incorrect. Because maturinn is masculine, the describing word must always take the masculine form góður. You only use gott with neuter words like kvöld.