Today a student asked me “How do you turn a noun into an adjective in German?” He wanted to say “banana bread” and “orange juice”. The answer is that German doesn’t form an adjective at all, but instead forms a compound noun out of the original words. So banana bread? Bananen + Brot = Bananenbrot. And orange juice? Orangen + Saft = Orangensaft. The last word in the compound determines the gender (and plural form) of the compound noun: das Brot, thus das Bananenbrot and der Saft, hence der Orangensaft.
About 30% of compounds require a connector between the combined words. These are most commonly –n-, –en-, –s-, –es– and sometimes –e-. The connector is sometimes the plural form of the first noun, as above: Banane (singular) → Bananen (plural), Orange (singular) → Orangen (plural). But no one rule governs the choice of connector. There are therefore words such as Tageslicht (day + light) and Tagebuch (day + book = diary), but also Tagtraum which combines two words (Tag + Traum day + dream) using no connector.
The joined words needn’t be only nouns. While the final element of a compound noun must be a noun, the first element an be an adjective, an adverb, a verb or verb stem, or a preposition.
Here are some examples of German compound nouns. See if you can tell what they mean. Click on the text of each compound to see the answer.
And there is no rule limiting the length of a compound. It can consist of a string of several German words:
How did you do?