Interest or Interests – What is The Plural of “Interest”?

“Interest” is one of those nouns that people sometimes have trouble transforming into the plural form. Is “Interests” correct? Or is it “Interest? And if both are correct, what’s the difference? This article will answer all of those questions, and explain the difference between both forms.

What is The Plural of “Interest”?

Both “Interest” and “Interests” can serve as the plural form, depending on the context. This is because “Interest” can either be a countable or uncountable noun, based on what it’s being used for. When it’s countable, you use “Interests”. When it’s uncountable, you use “Interest”.

interest or interests

“Interest” as plural is used when “Interest” refers to a curiosity regarding a specific subject, a wish to understand and know about a certain subject.

This form of interest can be understood by referencing the phrase “To be interested in”.

When you’re talking about several activities you enjoy, then “Interests” with an “s” at the end is the appropriate plural form to employ. This form of “Interest” could be considered as a synonym for “Hobby”.

Is It “Best Interest” Or “Best Interests”?

Both “Best interest” and “Best interests” can be used to convey the same idea of something being advantageous. Both phrasings are grammatically correct and can often be found used by native English speakers. They are very much interchangeable.

That being said, “Best interests” is slightly more common. This isn’t a strict grammatical rule, but in contexts where the “Interest” refers to something that’ll benefit the person, “Interests” sees more use.

It’s a distinction that most speakers do not pay much attention to, and no matter what phrasing is used, the listener will understand the core of the phrase with little issue.

Here’s a few examples that showcase common variations of the phrase:

  • It’s in your best interests to apply to all of these universities.
  • As a lawyer, it is our job to serve the best interest of our beautiful nation.
  • It’s in our best interest to seek out all possible options before any decision is taken.
  • You should look up that dealership, it’s in your best interest.
  • To move forward with proceedings was in our best interests.
  • It would serve the best interests of my client to look into these files.

When Should I Use “Interest”?

“Interest” should be used when referring to the action of being interested in something, or a feeling of curiosity regarding something.

The feeling of being interested in several things, then, is still conveyed with the singular “Interest”, because in this context “Interest” is considered an uncountable noun, and therefore doesn’t change.

Here’s a few examples of this particular use of “Interest”, if you’re still confused:

  1. My interest in magic and wizardry has been developing since I was young.
  2. I had an interest in law and government at the time, so I studied for the conference.
  3. Out of the batch of classes, my interest remained on the Literature, Chemistry, and Biology courses.
  4. Her interest is on Constitutions and the way that they evolve or don’t evolve over the decades.
  5. My interest in the way that public housing projects are organized remained after all this time.
  6. Their interest in our school, their school, and the third school was prominent and obvious.
  7. It’s an interest in several things, mainly law enforcement, that drove me to this major.
  8. Considering his interest in all of the houses on our street, we were very lucky.
  9. Our interest in going to an international conference and winning the race increased.
  10. It was an interest in multiple things that they nurtured over time.

When Should I Use “Interests”?

“Interests” as the plural form should be used when referring to multiple activities that the person enjoys doing, akin to the concept of a hobby.

This plural form of “Interests” is generally used when talking about several things that the person enjoys doing in some way, and develops on.

Here’s a few examples of this use of “Interests” to clarify any questions you might have:

  1. Her interests are fencing, horseback riding, and archery.
  2. My language interests are Spanish, English, Japanese and Portuguese.
  3. The company’s interests are stocks, bonds, trades and golden parachutes.
  4. His interests are the language of acting, the form that acting takes, and method acting.
  5. Typewriters, old ovens, victorian lighters and oil lamps are some of his antique interests.
  6. Her interests are mainly photography, economics, law, and modelling.
  7. My interests are mostly programming, designing and writing.
  8. Marketing and corporate studies are some of her interests.
  9. Their interests are baking, graphic novels, and painting.
  10. His interests are american football, playing guitar, and solving mysteries.

Is “Interest” Or “Interests” Used The Most?

According to information sourced by the Google Ngram Viewer, “Interest” sees a lot more use than “Interests”, though the gap between the two has lessened over the years.

interest or interests english usage

The data showcases the fact that since at least the year 1900, “Interest” has been used in literature significantly more than “Interests” has.

Throughout all of the information on the viewer, there has been no point in which “Interests” has seen more use than “Interest”.

However, this could partially be because we cannot separate the singular “Interest” from the plural, uncountable “Interest”.

Furthermore, the gap between the two has lessened over the decades, with information from 2019 pointing to the two terms being the closest they’ve ever been in amount of use.

If this trend continues, in the next couple of decades or so, “Interests” could overtake “Interest” as the preferred pluralized form of “Interest”.

Is It “In The Interest” Or “In The Interests”?

Both “In the interest” or “In the interests” are valid phrases, their usage depends on the amount of interest. “In the interest” is a phrase used to convey acting for the benefit of a person, or an entity. If there’s multiple reasons for this action, “Interests” is valid.

Here’s a couple of examples:

  • I’m acting in the interest of your father, not in my own interest.
  • That decision would go against the interests of the company, unfortunately.

Is It “Their Interest” Or “Their Interests”?

“Their interest” and “Their interests” can be correct. It depends on whether the “They” in the sentence has either a singular or multiple interests. If it’s just one interest, then it’s “Their interest”. If “They” have multiple interests, however, then “Their interests” is correct.

Here’s two example sentences:

  • Their interest in my future has been very heartwarming to witness.
  • Their interests in the geopolitical development of the region are real and valuable to us.