Dairy vs. Diary – What’s the Difference?

Dairy and diary are confusing because they are spelled with the same letters, but with the two vowels reversed. Using one of these words in place of the other is as easy as making a simple typo.

Unfortunately, these words do not mean the same things and cannot be substituted for each other. Each word has a clear usage case, which I will describe below.

What is the Difference Between Dairy and Diary?

In this article, I will compare dairy vs. diary. I will use each of these words in at least one example sentence, so you can see them in context.

Plus, I will show you a useful memory tool that you can use to help you choose diary or dairy for your next piece of writing.

When to Use Dairy

Definition of diary definition and definition of dairy definition What does dairy mean? Dairy can be a noun or an adjective.

As a noun, dairy refers to a place where milk is processed.

Here are two examples,

  • The fourth graders went to the nearby dairy for a field trip.
  • The FDA shut down the dairy because several of its buildings were not up to code.

As an adjective, dairy describes a product or food item made from milk. Here are a few examples:

  • Vegetarians do not eat meat, but vegans do not use any animal products, including dairy substances, leather, and honey.
  • Darlene has a dairy allergy, which means she cannot go with us to the ice cream parlor.
  • Karmanau visited a dairy farm just outside that zone and obtained a milk sample. –The Washington Post

When to use Diary

Define diary and define dairy What does diary mean? The word diary is a noun. A diary is a small book where one writes down the events of a day. In this way, it can be a synonym of journal in that word’s noun sense.

See the sentences below for examples.

  • Megan writes in her diary each night before she goes to sleep.
  • Karen is careful to hide her diary where her little brother would never be able to find it.
  • When Brian read his wife’s diary, he was dismayed by what he found in its pages.
  • In 2011, Alexander Masters was given 148 moldy diaries that had been found in a Cambridge dumpster. –The Wall Street Journal

Trick to Remember the Difference

dairy versus diary Now, let’s take a look at a trick to remember dairy vs. diary.

Diary is never an adjective, so dairy is your only option for that usage. As a noun, the choice becomes more complex.

Diary refers to a book where someone writes things. Dairy refers to something made from milk.

To make it easy on yourself, remember that Dairy Queen is an establishment that sells ice cream and other food items. Ice cream is a dairy product because it is made from milk, so by remembering that Dairy Queen sells products made from milk, you should be able to remember when to use each of these words.

Another way you can ensure that you use the correct term is to simply sound the word out. Diary and dairy have distinct pronunciations that will lead you to the correct spelling.


Is it dairy or diary? Dairy and diary are easily mixed up since they are spelled only one letter apart.

  • Dairy is a food product made from milk.
  • Diary is a book where notes are kept.

Both of these words are nouns, but only dairy can be an adjective.

Since Dairy Queen sells products made from milk, you can use that company’s name to remind yourself of the proper context for the word dairy.