One of two small round structures on the undersurface of the brain that form the terminals of the anterior arches of the fornix WordNet 3.0 & Open English WordNet

The mammillary bodies are a pair of small round bodies, located on the undersurface of the brain that, as part of the diencephalon, form part of the limbic system. Wikipedia

Part of the brain Wikipedia Disambiguation

Pair of small round bodies located on the undersurface of the brain Wikidata

Either of a pair of structures on the undersurface of the brain that, as part of the diencephalon, form part of the limbic system. Wiktionary

One of a pair of small round bodies, located on the undersurface of the human brain, that act as a relay for impulses coming from the amygdalae and hippocampi to the thalamus, and (as part of the diencephalon) form part of the limbic system. Wiktionary

Anatomy. Wiktionary (translation)