Compound nouns 

 1. what are compound nouns?

Words can be combined to form compound nouns. These are very common, and new combinations are invented almost daily. They normally have two parts. The first part tells us what kind of object or person it is, or what its purpose is. The second part identifies the object or person in question. Compound nouns often have a meaning that is different, or more specific, than the two separate words.

2. how are they formed?

 A compound noun is a noun that is made with two or more words. A compound noun is usually [noun + noun] or [adjective + noun], but there are other combinations (see below). It is important to understand

 and recognize compound nouns. Each compound noun acts as a single unit and can be modified by adjectives and other nouns.