In German, words formed from two or more separate words are very common. The gender and plural of the newly formed word are determined by the last word in the combination.
A complex compound word can be formed from:
1. two or more nouns: der Tisch + die Decke – die Tischdecke
das Haus + die Tür + der Schlüssel – der Haustürschlüssel
2. verb + noun: warten + Zimmer – das Wartezimmer
rasieren + Apparat – der Rasierapparat
3. adjective + noun: alt + Papier – das Altpapier
4. adverb + noun: links + die Kurve – die Linkskurve
In 30% of complex compound words, a connecting part is added to link the remaining elements. This can be a vowel – e or – (e)s, (e)r or – en. Unfortunately, there is no established rule for which combination or vowel is used in which words. Most often, however, e (s) is used when forming complex compound words.
lesen + die Brille – die Lesebrille, das Badezimmer
der Hund + die Hütte – die Hundehütte
die Geburt + der Tag + das Geschenk – das Geburtstagsgeschenk
die Gesundheit + der Minister – der Gesundheitsminister
die Schwangerschaft + der Test – der Schwangerschaftstest
der Student + der Ausweis – der Studentenausweis
die Straße + die Bahn – die Straßenbahn
In cases where -er is added, one of the words in the newly formed compound word is in the plural.
das Kind + das Zimmer – das Kinderzimmer
das Wort + das Buch – das Wörterbuch
And one more example of a complex compound word:
die Mehrzweckhalle
die Nummernschildbedruckungsmaschine