What Is a Common Noun?

A common noun is the generic name for a person, place, or thing in a class or group. Unlike proper nouns, a common noun is not capitalized unless it either begins a sentence or appears in a title. Common nouns can be concrete (perceptible to the senses), abstract (involving general ideas or qualities), or collective (referring to a group or collection).

All nouns can be classified as either common or proper. All nouns name something, but proper nouns name them specifically. Common nouns do not.

Examples :

They say that diamonds are a girl’s best friend.

If you want to be my best friend, the Blue Moon Diamond would be a great gift idea.

Usually, it will be quite obvious if a specific person, place, or thing is being named.

Example :

While cats are social animals, some may seem like solitary creatures.

A cat may scratch you if it is teased too much.

Seriously, you should watch yourself around Fluffy.

Ray likes to hike in the mountains.

Ray has climbed Mount Everest twice.

A girl rang the doorbell this afternoon while you were out.

Gigi rang the doorbell this afternoon while you were out.

Distinguishing between common nouns and proper nouns seems easy, so why do we really need to know the difference between them? The answer to that question is this: to assign capital letters correctly.

Common Nouns Are Lowercased

A frequent spelling error people make is to capitalize common nouns unnecessarily. Some words, like president, seem to beg for a capital letter because instinctively we want to emphasize their importance. But even this lofty title is a common noun if it does not name something or someone specific (in this case, a specific president).

Incorrect                    The United States has had four Presidents this century.

Correct                       The United States has had four presidents this century.

Incorrect                    George Washington was the first President of the United States.

Correct                       George Washington was the first president of the United States.

Incorrect                  In 1789, the tenure of president George Washington began.

Correct                     In 1789, the tenure of President George Washington began.

In the penultimate example, the fact that George Washington is named at the beginning of the sentence may tempt you to capitalize president afterward, but you must resist this temptation. Here, George Washington is referred to as the first president of the United States—that is, the first in a number of presidents of the United States. Thus, in that example, president is a common noun.

In business writing, the common compound noun board of directors is often incorrectly capitalized in this way. Although you may idolize your company’s board of directors and put them on the proverbial pedestal, board of directors is not capitalized unless it is part of a proper noun.

Correct                     My company’s board of directors met for six hours today and I had to take minutes.

Correct                     Because I so faithfully took six hours of minutes, I was invited to the Board of Directors’ Ball this Saturday.

This principle applies to every common noun, no matter how monumental its significance. Even if your noun represents the most momentous event the universe has seen, it must be named specifically to be proper and to don its capitals.

Correct                    Hubble and Einstein contributed to the theory of the cosmological expansion of the universe .

Correct                    The Big Bang is a theory regarding the cosmological expansion of the universe.