I was wondering if "vector" is countable or not. I've been using it in plural form (vectors) but I don't know if that is correct.

  • Certainly one can have multiple vectors (in the mathematical/engineering sense) -- 2, 3, 538. And I'm not offhand thinking of a context where "vector" would mean an uncountable mass (that wasn't infinite).
    – Hot Licks
    Oct 23, 2014 at 19:14

2 Answers 2


Yes, vector is countable, and the plural form is indeed vectors as mentioned in the Merriam-Webster Learner's Dictionary:

vector /ˈvɛktɚ/ noun

plural vectors


1 mathematics : a quantity (such as velocity) that has size and direction


If you search for "vectors" on Google Scolar you will also find hundreds of thousands of scientific publications using the plural form, so I would say it is definitely accepted to say vectors.

  • 2
    That's not how you find a definitive answer. Consult a good dictionary instead.
    – Kris
    Oct 23, 2014 at 20:06
  • @Kris The plural form was not mentioned in the dictionaries I consulted before thinking of going to Google Scolar to prove my point. But you are right. I found a dictionary I can use now, so I'll edit my answer.
    – Raizin
    Oct 23, 2014 at 20:25
  • I majored in Applied Math in college, so I think I'm more of an authority on if "vectors" than a dictionary compiled by English major types. "Vectors" is indeed cromulent.
    – JenSCDC
    Oct 23, 2014 at 20:38
  • 1
    Kris, when you're seeing hundreds thousands of mentions of "vectors" in its natural habitat, why on earth would you what to consult a dictionary??? Where do you think dictionaries get their definitions from, original documents or from thin air?
    – JenSCDC
    Oct 23, 2014 at 20:41
  • 2
    @AndyBlankertz Applied Math major here too. "Countable" has a specific meaning here, although I'm not personally a fan. I like singular and plural better. It is kind of a silly question to begin with. Asking about countability makes more sense for, say, "people" or "data" or "javelina" where there is some ambiguity in usage. Next: Is scalar countable? Ugh, yes.... Oct 23, 2014 at 21:18

To tell weather or not a noun is countable, you refer to a dictionary.

Here's what LDOCE says:

vec‧tor [countable] technical

  1. a quantity such as force that has a direction as well as size
  2. an insect or animal that passes disease from one person to another [= carrier]:
    Mosquitoes are feared as vectors of malaria.
  3. in biology, an animal or human cell that is used to carry DNA from one cell to another to produce a clone

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