If you examine the words airplane, newspaper, paperclip, or postman, you can see that these words actually contain two distinct words that could be used separately. Joining these two independent words together creates what is called a compound word. Air and plane come together to form airplane, or paper and clip becomes paperclip.

The compound word is thus two words joined to make a new, and usually more specific word applicable to the circumstances. For instance the word news can mean many things. When combined with the word paper, which could also refer to several different types of papers, the compound word, newspaper, is well understood, and more specific. Nevertheless, you’ll often see people refer to a newspaper as “the paper,” though technically the former word is more accurate and more descriptive.

When you join two words together to form a compound word, changes tend not to occur in spelling of the words. Instead, the major change is simply deletion of spaces between the words. It’s in essence a marriage of words, where two words become one. There are some exceptions to this rule of marriage. Just as many women now use a hyphenated last name when they get married to keep their pre-marriage last name, some compound words may be hyphenated instead of being directly together. Compound words not joined by a hyphen are called solid compounds, while words joined by a hyphen are hyphenated compounds.

It’s important to understand the use of compound words because some of them, whether solid or hyphenated, may have different definitions when the words are compounded, rather than merely used consecutively in a sentence. The compound word, overall, takes on a slightly different meaning when written as over all. Consider the following two sentences:

Overall, I enjoyed the film.

The film was picked over all the others to win the Academy Award.

In the first example overall is a transitional word or a summing up word. It could be used as a synonym for words like in conclusion, or to sum. In the second example the words over all, imply above all the others or over all the others. Over all means superior to rather than to sum up.

When choosing whether to join words, either by hyphen or deletion of space, it’s a good idea to consult a dictionary for the correct usage. There are many words that may be compounded, and sometimes it remains guesswork as to whether or not two words should be joined, and if so, when that joining is most appropriate. Generally, when you are joining two words that are not usually compounded, you use a hyphen to express a relationship, instead of creating a compound word that doesn’t actually exist. Still, check with a dictionary first to see what the normal recommendation is for the specific words you wish to join.