In the last few years an Internet meme has been going around that "poison" is a substance that has a negative effect when ingested, while "venom" has to be injected. Ergo, "poisonous snakes" should really be "venomous snakes" etc. I have also heard people repeat this definition both in-person and online.

However, this doesn't align with my intuition, nor can I find a source to substantiate this distinction. From my research, "poison" derives from the same root as "potion", so there is some reason there for it to mean exclusively a substance that is eaten. But one can very easily make the argument it means a liquid that needs to enter the body via some means to have an effect. On the other hand, "venom" is from "venenum", which itself shares meaning with "poison". In French for example you would use either "venimeux" or "toxique", but there's no word for "poisonous" with a root derived from "poison". Same for Italian. You would definitely describe a "poisonous beverage" as "venimeux".

From this it seems there is no real historical justification for the contemporary usage I see repeated around the Internet. The modern descendants of Latin themselves don't make this distinction and use "venom"-derived words for "poison". I know a bit of Russian too and there is just one word for both "venom" and "poison" when speaking of substances and a completely different word for the metaphorical meaning of speaking negatively with passion (i.e. to spit venom).

Can anyone point to an actual historical reason for the modern definition of "poison has to be eaten, while venom has to be injected"? Or is this a new development in English?

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    "Venom" is a specific class of poison produced by an animal and injected with a bite or sting. "Poison" can be injected, inhaled, swallowed, or applied to the skin. – Hot Licks Oct 13 '19 at 12:35
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    The key difference is that venom isn't poisonous. People can drink it without obvious ill effect. Rattlesnakes are not poisonous, many people do eat them, without obvious ill effect. – Ray Butterworth Oct 13 '19 at 13:53
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    Your first paragraph associates both with injection. Was one supposed to be associated with ingestion instead? – Lawrence Oct 13 '19 at 14:08
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    Look up both on Etymonline. – marcellothearcane Oct 13 '19 at 14:44
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    You need to add research. For instance, AHD has poisonous: adj ...b. capable of harming or killing by poison. So a cobra can legitimately be described as a poisonous snake (or, if you check, a venomous snake). There is an overlap in meanings between 'poison' and 'venom' (that probably doesn't correspond exactly to that between 'poisonous' and 'venomous'. There will be precisionist and broader definitions. "The terms are often used interchangeably, but ‘venom’ and ‘poison’ are not the same thing" shows confusion as to how English works. – Edwin Ashworth Oct 13 '19 at 15:55

TLDR: the distinction actually exists in modern-day French, and this may be the source of the restriction of venom and venomous to injected toxic substances.

Walker's pronouncing dictionary from 1828 has the definitions

poison: that which destroys or injures life; venom.
venom: poison.

The 1892 Webster's High School Dictionary has the definitions

poison: Any substance noxious to life or health ; venom ; ruin ; malignity.
venom: Poison; spite; malice.

So it appears that, in the common language at least, there was no difference in meaning during most of the 19th century. The difference certainly exists today in the scientific literature.

The distinction between venomous and poisonous may come from French, which has two adjectives that originate from the same word in Latin: venimeux and vénéneux. Today, the Larousse dictionary says that French uses venimeux for toxic substances that are injected (or maybe absorbed through the skin), and vénéneux for toxic substances that are ingested (or maybe absorbed through the skin).

The TLFI says:

La spécialisation d'empl. (vénéneux à propos du monde végétal et venimeux à propos du règne animal) plus marquée dep. le xviiie s., n'a cependant jamais été complètement réalisée.

The specialization in usage (vénéneux for plants and venimeux for animals), more marked from the 18th century on, has never been completely realized.

I don't know how the distinction in French between venimeux and vénéneux came into existence. It certainly seems to predate the distinction between venomous and poisonous in English, which might indicate that we got the distinction from the French.


As explained by science.org the main difference between venom and poison is the way they are delivered to the victim.

The terms are often used interchangeably, but ‘venom’ and ‘poison’ are not the same thing. True, they’re both a toxic substance that can potentially harm or kill you, but the main difference lies in the way they are delivered to the unfortunate victim.

Poison is a toxin that gets into the body via swallowing, inhaling or absorption through the skin. Poisonous animals tend to be more passive-aggressive—they often won’t actively attack their prey, but release their toxins as a result of being eaten, touched or disturbed. A cane toad, which secretes toxins from glands on each shoulder, is a poisonous animal. It has to be ingested or licked to cause harm. Poison ivy is an example of a poisonous plant—touching it can result in an itchy and sometimes painful rash.

Venom is a specialised type of poison that has evolved for a specific purpose. It is actively injected via a bite or sting. Because venom has a mixture of small and large molecules, it needs a wound to be able to enter the body, and to be effective must find its way into the bloodstream. For this reason, venomous animals are more active in defending themselves. A taipan, which injects venom through syringe-like teeth, is a venomous animal. So are jellyfish, which inject venom into skin using venom-filled harpoon-like structures that shoot out from cells along their tentacles when touched.

  • " ‘[V]enom’ and ‘poison’ are not the same thing" and "Venom is a specialised type of poison" is at best very confusing. As is often the case, the distinction between the scientific register(/s) and everyday English is not explained clearly. This is perhaps most obviously exemplified when the hypernymic polysemy of 'animal' is not disambiguated. A bird is an animal, but not an animal. – Edwin Ashworth Oct 13 '19 at 16:11
  • Not sure why you'd lick a cane toad, but I suppose it's been done enough times for us to be told not to. – marcellothearcane Oct 13 '19 at 16:38
  • This does not justify the meaning. I understand how the distinction is taught today, I'm asking why the distinction exists in English given it doesn't exist in Latin or modern descendants of Latin. – Moshev Oct 13 '19 at 17:55
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    @Moshev - so you are asking for etymology, are you? – user 66974 Oct 13 '19 at 18:01
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    @marcello: Licking a cane toad allegedly affects you enough to make you high without lasting damage. I have no idea of the truth of this pre-Internet meme, but it remains popular enough for teenagers to experiment. – Tim Lymington Oct 15 '19 at 12:07

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