noun
sea coconut; coco de mer; double coconut
Refers to the palm species Lodoicea maldivica, known for its large seeds. The term is a botanical name; in everyday Japanese it is a specific, uncommon word.
オオミヤシはセーシェル諸島に自生する珍しいヤシの一種だ。
The sea coconut is a rare type of palm native to the Seychelles.
植物園で巨大なオオミヤシの実を見た。
I saw a huge coco de mer fruit at the botanical garden.
The Japanese name オオミヤシ literally means 'large-fruit palm'. The exact historical derivation is uncertain, but it is a straightforward descriptive compound.