hippocampus

American  

[hip-uh-kam-puhs] / ˌhɪp əˈkæm pəs /

noun

hippocampi plural

1. Classical Mythology. a fish-tailed horse of the sea that was ridden by the sea gods.

2. Anatomy. an enfolding of cerebral cortex into the lateral fissure of a cerebral hemisphere, having a major role in learning, emotion, and memory, and named for the seahorse shape of its cross section.

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hippocampus British  

/ ˌhɪpəʊˈkæmpəs /

noun

1. a mythological sea creature with the forelegs of a horse and the tail of a fish

2. any marine teleost fish of the genus Hippocampus, having a horselike head See sea horse

3. an area of cerebral cortex that forms a ridge in the floor of the lateral ventricle of the brain, which in cross section has the shape of a sea horse. It functions as part of the limbic system

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hippocampus Scientific  

/ hĭp′ə-kăm′pəs /

hippocampi plural

1. A convoluted, seahorse-shaped structure in the cerebral cortex of the temporal lobe of the brain, composed of two gyri with white matter above gray matter. It forms part of the limbic system and is involved in the processing of emotions and memory.

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Other Word Forms

Derived Forms

• hippocampal
  adjective

Inflected Forms

Nouns

• hippocampi
  plural

Etymology

Origin of hippocampus

First recorded in 1575–80; from Latin hippocampus, hippocampos, from Greek hippókampos, equivalent to hippo- hippo- + kámpos “sea monster”

Explanation

A hippocampus is a complex neural structure that's part of the brain. Your brain has two hippocampi, and they're important for memories and emotions. This word has a complex history. Originally, it meant a seahorse, and it has also meant a small fish that resembles a seahorse. That resemblance is why the brain structures known as the hippocampus major and hippocampus minor have that name: they look kind of like seahorses too. The hippocampi are found on the floor of your brain's ventricles, and they are vital to feeling and remembering. Without your hippocampi, you wouldn't be who you are.

Example Sentences

See Examples For:

hippocampus hippocampi

Rats that ate high-fat and high-sugar diets early in life later showed weaker communication between the gut and the hippocampus.

From Science Daily ● Jul. 29, 2026

The researchers found that neurons in the hippocampus consistently detected these unusual tones.

From Science Daily ● Jun. 29, 2026

The scans showed that fish oil supplements did not slow shrinkage of the hippocampus, a brain region critical for memory that is commonly used as a marker of brain aging and Alzheimer's risk.

From Science Daily ● Jun. 29, 2026

The researchers point to areas such as the hippocampus as possible contributors that were not affected by the treatment.

From Science Daily ● Jun. 3, 2026

“We ...” She slumped against the neck of the hippocampus and instandy fell asleep.

From "The Sea of Monsters" by Rick Riordan

Subsequently, their hippocampi were isolated and underwent gene expression analysis to identify genes with varying expressions between rodents with extremely low anxiety and those with severe anxiety.

From Science Daily ● Jan. 22, 2024

After nearly 1 month, the number of new neurons in the rodents’ hippocampi had doubled.

From Science Magazine ● Feb. 3, 2022

The team screwed tiny wireless devices into the skulls of three bats to track their flight paths and collect data from electrodes implanted inside their hippocampi.

From Nature ● Jan. 11, 2017

Studies have confirmed, for example, that London taxicab drivers grow larger hippocampi as they learn to navigate London’s convoluted roadways.

From Scientific American ● Aug. 29, 2012

The hippocampi were still skittish, but they stopped swirling around me quite so fast.

From "The Titan's Curse" by Rick Riordan