Most definitions say that it is a component of blood that has been in a centrifuge, but I haven't seen any definitions that is associated with sci-fi.

I often came across this word when people talk about something that can be injected into the bloodstream for unusual effects that are beyond what we can do today.

An example would be a serum containing tiny little machines called nanites or nanobots. Some might call it nanosubmarines, but I'm sure they pretty much mean the same thing.

In other uses I have seen, serum was used as a dye, so that certain tissues would be seen and marked for manipulation. I think this exists in real life, but there is also something called truth serum.

  • So, what exactly does serum mean in this context?

closed as too broad by Valorum, Rebel-Scum, Jenayah, Edlothiad, Mat Cauthon Mar 17 at 14:11

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    It’s an extension of the first definition at the Macmillan dictionary: “a liquid that is put into someone’s blood to help them fight an infection or a poison.” – James McLeod Mar 17 at 11:39
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    The most common use is an injectable liquid. What it does depends on the story. A truth serum makes the recipient tell the truth. A serum for Denebian Spotted Jungle Fever cures Denebian Spotted Jungle Fever. – WhatRoughBeast Mar 17 at 14:37
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    Definitions of words aren't on-topic here, especially when it's a common medical term – Valorum Mar 17 at 16:08
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    Although, as per the recent Deadpool question, a specific quote is admissable. – FuzzyBoots Mar 17 at 21:09

In real world biology, serum is the clear yellowish fluid left over from blood when you separate out the blood cells, normally by spinning in a centrifuge. It can still contain antibodies among other things, but no red cells.

In recent decades the word has also been misappropriated by elements of the cosmetics industry for use in describing some of their products to give a veneer of scientific authority to them.

there is also something called truth serum

Neither pentathol nor any other drugs with similar effects are a serum in the proper scientific use or definition of the word, despite often being colloquially referred to as a truth serum.

What does the term 'serum' refer to in science fiction stories?

In science fiction it pretty much means whatever the author wants it to (or thinks it does).

In my experience it most often means an injection that bestows long term (or permanent) physical / physiological advantage or improvement of some sort. The "super soldier" serum that made Steve Rogers into Captain America is a prime example.

Their effects often bear closer resemblance to something that might be achieved with gene therapy than anything a real serum can do and take instant or near instant effect from a single injection. This in no way is meant to suggest there is anything remotely realistic about some (or even any?) of their effects, simply that a closer ("closer", not "close") real world analogue for them would often be gene therapy rather than the word serum that is most often used for them.

But the effect of a "serum" in science fiction can be anything, so really it defies any definitive definition other than simply saying that it's any sort of handwavium that bestows powers or effects if injected.

Google: serum meaning

Cambridge Dictionary : Serum

Quora : serum in biology

  • Can you take the parenthetical out of code mark up? It makes it harder to read and doesn't work well with screen readers. – Adamant Mar 17 at 17:10

In addition to the other two answers, serum could also be a blind idiot or false friend translation. In German, serum has mutated in common use from the scientific definition via antiserum to become medication in a more general sense.

Compare the use of truth serum in English.


Apart from being part of the blood, "Serum" might also mean medicine that is made from blood.

E.g. Merriam-Webster names as a possible meaning:

medical : serum from an animal's blood that can be added to a person's blood to prevent or cure disease

From there it's speculation, but it is easy to imagine how this would come to be used as a synonym for any sort of concoction that has active ingredients (as in, "if a serum makes you healthy, why shouldn't a super serum make you better than healthy"). So a serum is (usually) an injection that makes you in some way special (e.g. the "Super Soldier Serum" from Captain America).

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    "Apart from being part of the blood, "Serum" might also mean medicine that is made from blood" not really, it's part of the blood, it's sometimes used for medical purposes because it still contains antibodies & hormones, you are conflating a use of serum as somehow meaning it's actually something different, it's not. – Pelinore Mar 17 at 12:20
  • @Pelinore you might want to send this as a correction to Merriam-Webster (it's their definition that I linked and quoted). – Eike Pierstorff Mar 17 at 12:34
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    ^ nope, I've read their definition & it looks fine to me, you've just (after a fashion) misappropriated it :) to my mind the definitions in the link you provide clearly state an antiserum is a serum containing antibodies & that a serum comes from blood, what you've said seems to me to say an antiserum is something other than part of the blood "Apart from being part of the blood, "Serum" might also mean" ~ but maybe it's just the way I'm reading it? – Pelinore Mar 17 at 13:42

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