Does anyone know the history of the word jellyfish and how it was defined and popularized?

OED lists a usage in 1707, but that is referring to a gelatinous vertebrate fish.

They start showing uses as we know it today (albeit hyphenated) around 1841.

The reason for asking is that from a scientific perspective, it is a poorly-defined, non-taxonomic category. Some animals clearly should be called jellyfish, but lots of other things (siphonophores, comb jellies, even salps) are lumped in there where they may not belong.

Related, Latin languages use medusa (or similar) for English "jellyfish". What are some other common names in other languages?

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    Most (if not all) biological categories that arise in natural language are scientifically ill-defined and non-taxonomic. ‘Jellyfish’ is quite logical to me: it’s those jelly-like animals that swim around in the sea. A fairly indistinct and vague category, probably even intentionally so. I’m not sure I understand what it is exactly you’re asking about … Oct 23, 2013 at 20:44
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    OED specifically says the 1707 usage fish of the genus Plagyodus or Alepisaurus, family Scopelidæ is obsolete. The second sub-entry (popular name of various acalephs, medusas, or sea-nettles, from their gelatinous structure) was first recorded 1841. I can't see anything here that meaningfully constitutes an On Topic ELU question. Oct 23, 2013 at 22:04
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    Thanks FF. Those are the same passages that I was referencing in my question. I am asking because I would like to get an idea of what the early users of this term meant by it — how broadly the applied the concept. Would they have called this or this a jellyfish or something else? Maybe it is unknown or unknowable. I have published papers and videos about the shortcomings of the term, and am seeing if anyone has any helpful insights going forward.
    – beroe
    Oct 23, 2013 at 23:12
  • @beroe if that is what you're asking, please edit your question so that is clear. Anyway, people from 1707 had probably never laid eyes on either of the two stunningly beautiful beasties you linked to. If they were known, I doubt they would be well known enough to have a common name.
    – terdon
    Oct 24, 2013 at 0:00

1 Answer 1


This is what the online etymological dictionary has to say on the subject (not much as it happens):

jellyfish (n.)
popular name of the medusa and similar sea-creatures, 1796, from jelly (n.) + fish (n.). Earlier it had been used of a type of actual fish (1707).

I would guess that the name comes from the simple fact that jellyfish look like they're made of jelly. If you've ever held one in your hand you will agree that the similarity is striking. I doubt you will find any clearer etymology than that.

As for why it is used as a popular name for a variety of marine animals, the answer is simple ignorance. Common animal names do not stem from any taxonomical knowledge, they come from what ordinary people (people who are not professional taxonomists) see. That's why you have things like the killer whale, Orcinus orca, which is actually a dolphin or the "toothed whales" which include the sperm whale, Physeter macrocephalus, but are not true whales (Mysticeti). For an even clearer case, think of the sea horse which is quite clearly not a horse of any kind yet the reasons for calling it so are obvious the second you lay eyes on one:

enter image description here

As for medusa, it is actually Greek, not Latin and can be traced back to the mythical beast. Apparently, Linnæus (the father of modern taxonomy) named the genus because of their long tentacles. Asking for synonyms in other languages is off topic here but I can confirm that the jellyfish is called a medusa or similar in most Latin languages (including French, Spanish, Catalan and Italian) and in modern Greek.

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