LEARN ENGLISH UNCOUNTABLE COMPOUND NOUNS
Compound nouns are formed by more than one word, although they work as a single
word within the sentence. We use compound nouns when a single noun is not clear
enough to name a person or object. There are several types of compound nouns in
English: Noun + preposition + noun
washing up liquid (líquido lavavajillas) Noun + preposition or preposition + noun
drying-up (deshidratamiento) Verb + adverb or preposition
make-up (maquillaje) Noun + adjective or adjective + noun
junk food (comida basura)
Some compound nouns are uncountable and this happens when they name an object that cannot be counted.
We have installed air-conditioning at home. (Hemos instalado el aire acondicionado en casa)
In this example we are using the compound noun "air-conditioning" in its singular form because we cannot count it. We can only count the "air-conditioning units".
There are several ways of writing the compound nouns: