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.

You may have noticed that the compound noun can be written either as a single word (toothpaste), as a word with a hyphen (ccoking-oil), or as two words (paper clip). There are no clear rules about this. A good rule of thumb is to write the most common compound nouns as one word, and the others as two words.

The rules on whether to put a hyphen, a space, or nothing between the words in a compound noun are inconsistent. For example:

• inkwell , ink well , ink-well 
• fulltime , full time , full-time 
• waterbottle , water bottle , water-bottle 

It is best to use a spellchecker or a dictionary to see what versions of the word are acceptable.