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What Is the Plural of Hippopotamus?

G. Wiesen
G. Wiesen

The plural of hippopotamus is “hippopotamuses,” though in many contexts, the Latin plural form of “hippopotami” can also be used. While both plural forms are relatively acceptable, especially when used in informal contexts, many dictionaries list “hippopotamuses” as the first entry for the plural of hippopotamus. Despite this, however, many people feel that “hippopotamuses” seems silly, both visually and when said aloud, and often reminds people of the over-pronunciation of the word in the song I Want a Hippopotamus for Christmas. This causes many people to use the other form of “hippopotami” instead, though the increased usage of “hippo” has also lead to the use of “hippos” in many instances.

Since there are essentially two correct words that can be used as the plural, there can be a great deal of confusion over which word someone should use. If someone is trying to pluralize the word “hippopotamus” in a formal context, such as a school paper or for a work report, then the word “hippopotamuses” should typically be used. This is considered the correct plural in English and avoids any of the issues that may arise from using the Latin form. Despite the fact that this may seem lengthy or somewhat silly in appearance, it is correct English and should be accepted by any teacher or employer.

Close-up of a hippo head and eye.
Close-up of a hippo head and eye.

The word “hippopotami” is also correct as the plural of hippopotamus, however. Since this uses the Latin plural form, it may be considered somewhat informal or inappropriate in some settings in which the English plural may be preferred. This depends a great deal on the individual preferences of those who may be reading or hearing the words, however, so people looking to use the plural of hippopotamus in a school paper or report should consult their teacher to ensure proper usage for that setting.

"Hippopotami" can be used as a plural of hippopotamus.
"Hippopotami" can be used as a plural of hippopotamus.

Since the word hippopotamus has been shortened to “hippo” in many settings, the use of the plural word “hippos” can also avoid the entire issue regarding the plural of hippopotamus. This shortening is often seen as a very informal word, however, so it should usually be avoided in contexts in which formality is needed, such as scholarly or business writings. When spoken aloud, however, the word “hippopotamuses” can become laborious to say, and so “hippos” is often acceptable in that context. Like many animals, a gathering of hippopotamuses has a particular name and such a group is referred to as a “bloat” of hippopotamuses.

Discussion Comments


I'm sure that hippopotami are not dangerous as long as one leaves them alone. Any wild animal is bound to feel threatened when humans get too close. They are not domesticated so they need to be given their space.

As for which plural of the word is correct, the article has already clarified the answer. Hippopotamuses is right. I say hippopotami out of habit. I don't think my English teachers ever taught this. I must have come to this conclusion on my own because I did take Latin in college and the -i addix seems like the logical one when hippopotamus is made plural.


@umbra21-- I recently learned that hippopotamuses kill many humans every year. It was a shocking bit of news to me. When I was a child, I had a hippopotamus stuffed animal with two little baby hippopotamuses in its front pocket. It was my favorite stuffed animal and I played with it for years. So it's difficult to digest that they're not very friendly animals.


I'd personally either use hippopotami or hippos when referring to the plural of hippopotamus. I think these just sound better. I realize that students should stick with "hippopotamuses" in their assignments. But in regular conversation, I wouldn't want to use that. Even though it may be the correct form, it just sounds incorrect and strange. It's good to know what the dictionary says is correct though. This discussion itself could be a nice conversation ice-breaker.


@umbra21 - They might look awkward on land, but they can actually outrun a human, which is another reason they can be deadly. So I don't think it's that strange they were named after horses.

Although apparently they are most closely related to whales and dolphins. And I also want to point out that they are a threatened species, so you can hardly blame them for being aggressive towards humans.


@browncoat - Well, I can definitely see why there might be a negative term for a group of hippos. I mean, they are one of the most deadly animals in Africa in terms of human deaths. And they aren't even killing for food or when they feel like they are threatened. Apparently they are just bad tempered and will crush anyone who makes them mad.

And, frankly, they look kind of bloated. I mean, I think they are cute as well, particularly the baby ones, but they have very tightly stretched looking skin and they are heavy-set, because they spend most of their time in the water. I think the word is very appropriate. Probably more so than the word hippopotamus itself, which basically means "river horse". I'm not sure a four legged animal could look more different from a horse.


I'm not sure I approve of the group of hippos being known as a "bloat" of hippos. They are actually quite cute and interesting creatures and the word bloat just seems like it's completely negative.

I usually like using the correct word for a group of animals, because it usually seems much more fitting than a generic word, but I think in this case I might just keep calling them a herd.

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    • Close-up of a hippo head and eye.
      By: photo 5000
      Close-up of a hippo head and eye.
    • "Hippopotami" can be used as a plural of hippopotamus.
      By: sattapapan tratong
      "Hippopotami" can be used as a plural of hippopotamus.